Quotes of the Day

He was one of hundreds of rescue workers who combed through the wreckage last week looking for survivors in the scorched and twisted compartments of a commuter train at Madrid's El Pozo del Tío Raimundo station. When he came across an unremarkable sports bag, he assumed it belonged to one of the victims and put it aside; at some point amid the grim triage, the bag was taken to a local police station, where it was added to a mountain of unclaimed personal possessions—purses, briefcases, shoes, coats, laptop computers. In the chaotic aftermath of the Madrid bomb attacks, no one thought to open the bag.

And then its alarm went off. At 7:40 p.m., exactly 12 hours after a series of bombs had gone off on four trains, a mobile phone in the sports bag sounded an alarm, according to the Madrid daily El País. When investigators looked inside for the phone, they found it attached to two copper detonators, which were connected to 22 lbs. of a gelatinous dynamite. The bag was stuffed with nails and screws to heighten the bomb's destructive power. For some reason, the device did not detonate. Instead it became the biggest break yet in the hunt for those responsible for the massacre in Madrid.

A mobile-phone bomb is a SIMple but effective way to commit mass murder from a distance. The tactic worked 10 times during the Thursday-morning rush hour in Madrid as powerful explosives ripped open carriages, killing some 200 commuters and wounding more than 1,500 others. Like the 9/11 attacks, the Madrid bombings were impeccably timed to kill ordinary people on their way to work, and both left unforgettable tableaux of pain and destruction, the kind terrorists regard as spectacular. Not all the bombs took lives, though. Two similar devices were destroyed by police in controlled explosions. And thanks to a terrorist's mistake and a rescue worker's inadvertent discovery, the final bomb survived. It proved to be lucky 13 for the investigators. The Motorola handset and its internal identity, or SIM, card supplied the vital clues that led to the arrests on Saturday afternoon of five suspects—three Moroccans and two Indian nationals. The five were held in connection with illegal manipulation of the phone and its SIM card.

Two Spanish citizens of Indian origin were also questioned by the police. According to a Spanish government official, at least two and possibly all four of the Indians ran a shop in Madrid where they sold—not always legally—prepaid SIM cards. Spanish defense analyst Rafael Bardají suggests they may have been unwitting collaborators. "Perhaps the poor chaps were only the people who prepared the illegal phones," he says. "The question is, to whom did they sell the phones?"

In announcing the arrests, Interior Minister Angel Acebes said, "We're continuing to work on all fronts," referring to the possibility that the Basque terrorist group ETA may have been behind the attacks, "although these arrests open an important new avenue of investigation." It was a far cry from even earlier that day when the minister still considered ETA the prime suspect. Spanish and French authorities say the Moroccans may be linked to the synchronized suicide bombings that killed 33 people in Casablanca last May. Government sources in Morocco are more emphatic, telling TIME there was evidence that all three had connections to the extremist groups believed to have directed those attacks, Salafia Jihadia and its offshoot cell Assirat al-Moustaqim (Straight Path). These groups, Moroccan sources say, are associated with Osama bin Laden's al-Qaeda network. The Casablanca operation loosely resembled the Madrid massacre: there were well-orchestrated blasts in five locations, and in each instance the explosives were carried in bags or rucksacks. One important difference, though: the Casablanca attacks were all suicide bombings. So far, Spanish investigators have found no evidence that suicide bombers were at work in Madrid. "They were in Spain for a reason," says independent expert Roland Jacquard. "The thesis now is ... they've been continuing work there to replicate the Casablanca strike in even bolder form."

The Islamic connection got another boost late on Saturday night when Acebes announced that the Spanish government had retrieved a videotaped message from a man purporting to be al-Qaeda's military spokesman in Europe. The Madrid television station TeleMadrid had received a call from a man with an Arab accent saying a tape had been placed in a wastebasket near the city's main mosque and the municipal morgue. Police secured the area, picked up the tape and translated it. According to Acebes, a man speaking Arabic with a Moroccan accent identifies himself as Abu Dujan al-Afgani, a military spokesman for al-Qaeda in Europe, and says, "We declare our responsibility for what happened in Madrid ... It is a response to your collaboration with the criminals Bush and his allies ... There will be more if God wills it. You love life, and we love death ... if you don't put an end to your injustices, more and more blood will run." Spanish law-enforcement officials are checking the tape's authenticity.

This was, in fact, the second claim of responsibility from an al-Qaeda-related group. On Thursday night the London-based daily Al-Quds al-Arabi received an e-mail from another group claiming authorship for the Abu Hafs al-Masri Brigades, named for an al-Qaeda leader killed in a U.S. missile attack in Afghanistan. The message said one of its "death squads" had planted the bombs to settle "old accounts with Spain ... America's ally in its war against Islam." The statement went on, "The death squad succeeded in penetrating the crusader European depths and striking one of the pillars of the crusader alliance" and warned that another attack against the U.S. is "90% ready—and coming soon." The New York City police department sent, and Morocco planned to send, teams of investigators to Madrid, and the FBI also offered assistance; all hoped to gather intelligence they might need at home.

The Brigades has made bogus claims, including authorship of last summer's power outage in the northeastern U.S. But the Brigades also claimed to have carried out November's bombings of synagogues and British targets in Istanbul, in which 61 were killed, and the August bombing of U.N. headquarters in Baghdad in which 22 died. Some intelligence experts take the Brigades seriously—they could be "the new military wing of al-Qaeda in charge of external jihad," says Mustafa Alani, a Middle East security expert at London's Royal Services Institute for Defense and Security Studies—but no one has verified its role in those attacks. Even so, there is no question that the November bombings of the British consulate and a British-based bank in Istanbul showed that bin Laden's disciples were able to target Western interests at Europe's doorstep. If Madrid turns out to be the Islamists' handiwork, it means al-Qaeda has blasted open the door and stormed inside.

The arrests helped clear the confusion that had descended on Madrid in the aftermath of the attacks. Before anyone knew what was in the sports bag, most Spaniards instinctively fingered ETA, which has killed more than 800 people in a campaign of terror spanning four decades against the Spanish state. Just hours after the attacks, Acebes was adamant that there was "no cause for doubt" that ETA was to blame. Government officials and members of the ruling Popular Party (PP) pointed to what they said were hallmarks of ETA involvement: the bombings took place just three days before Sunday's general election, which ETA had vowed to disrupt; it had targeted the railway system before; and only last month Spanish police had foiled ETA attempts to transport large quantities of explosives into Madrid.

But the train blasts also differed from the Basque group's traditional modus operandi in important ways: the absence of warning, which ETA usually gives; the deliberate targeting of civilians; and the sheer scale of the operation. Despite the government's professed certainty of ETA's guilt, doubts began to creep in. Then on Thursday evening, Acebes announced that in Alcalá de Henares, a town about 19 miles northeast of Madrid where three of the ill-fated trains had originated and which the fourth had passed through, police found an abandoned white Renault Kangoo van containing seven copper detonators and a tape of Koranic verses recited in Arabic. That discovery harked back to the hours after the attacks in New York City and Washington on Sept. 11, 2001, when a rental car was found in the parking lot of Boston's Logan airport containing flight manuals in Arabic. That vehicle was the start of the trail that led American investigators to al-Qaeda. The van in Alcalá de Henares was another piece of evidence that pointed to Islamic radicals rather than Basque terrorists.

If there had been no warning from ETA, there had certainly been a declaration of intent from al-Qaeda. A tape purportedly of bin Laden, aired in October, had singled out Spain for retribution because of its government's staunch support for the war in Iraq. And documents on an Arabic website studied by Norwegian defense researchers in the past four months indicated that al-Qaeda was considering attacks on Madrid before the election. The 42-page document, titled "Jihad's Iraq," had been submitted to the discussion forum of a politically oriented website that no longer exists, according to Brynjar Lia of the Norwegian Defense Research Establishment. The section of the report devoted to Spain read in part: "We must exploit to the maximum the proximity of the election in Spain ... We believe that the Spanish government cannot tolerate more than two or three attacks before it will be forced to pull out" of Iraq. According to Lia, the document seems authentic, though he emphasizes that it contains no specific attack orders: "It's an overall guideline for strategies that the jihadis should pursue in the future." If that was all speculation, the van and the sports bag now provided Spanish investigators with real physical evidence.

And it didn't take them long to connect the dots. Nearly 24 hours before Acebes announced the arrests, Spanish authorities were warning French security services that the Madrid blasts could indeed be the work of an Islamic group. Security sources told TIME that this was one of the reasons the French government boosted its security status to red, its second highest state of alert. Paris was already concerned about the possibility of an attack by an Islamic terrorist group. In a recent taped message, bin Laden's deputy Ayman al-Zawahiri explicitly warned of retribution because of France's ban on Muslim head scarves in public schools. The Spanish intelligence forced France to consider itself in the cross hairs, according to a French official. "We know if we're not next, we're after the ones who are next," he said. "And that's what everyone in Europe is thinking to themselves today."

Back in Madrid, news of the arrests brought about a shift in the political mood just hours ahead of the general election. Until then, analysts had believed that widespread anger at ETA would favor departing Prime Minister José María Aznar's Popular Party, which has advocated a hard line against the Basque group. Some opponents charged the government with exaggerating the evidence against ETA and downplaying the al-Qaeda theory for political gain. Analysts suggested that if voters believed al-Qaeda was responsible, they might be inclined to take some of their anger out on the PP, which had put Spain on bin Laden's hit list by signing up for the U.S.-led war in Iraq. "Yesterday, we were marching in mourning. Tonight, it's out of revulsion at the politics that produced this terrorism," said Francisco Rodriguez, a middle-aged insurance-firm employee. "I hold the government responsible for the deaths on Thursday because we went out to support an unjust war."

To be fair, it wasn't just politics that led the Spanish government to see the attacks through an ETA prism. The Feb. 29 arrest of the alleged ETA operatives with their vanload of explosives was not the only recent attempt foiled by Spanish police. Last Christmas Eve, Spanish police foiled an attempt by two ETA operatives to blow up a train bound for another of Madrid's major train stations, Chamartín. They caught one trying to put a suitcase packed with 62 lbs. of the explosive Titadine on the train before it left and later found another suitcase with 44 lbs. of the explosive already on board. And on Dec. 19, 2002, two men were apprehended carrying 287 lbs. of an unidentified explosive that police said the men had planned to place throughout Madrid and then detonate simultaneously.

If the style and scope of the Madrid attacks differed from some of the established ETA patterns, that may just be an indication that the group has changed a great deal. Since the arrest of most of ETA's top tier in a series of joint counterterrorist operations by France and Spain over the past decade, control may have passed to a generation of younger leaders who may be radical—or just plain inexperienced—enough to commit an atrocity like last week's train attacks in Madrid. A report on trends in terrorism published in December 2002 by the Council of the European Union, the E.U.'s ministerial-level policymaking body, cites the alarming rise within ETA of younger men from inside the culture of kale borroka, the Basque term for "street violence."

But public outrage over the attacks suggests that if ETA was behind them, it may have signed its own death warrant. "Some people think we drink champagne when attacks happen," says Ainhoa Osinalde, spokeswoman for Pagotxeta, a pro-independence group close to Batasuna, the banned party often described as ETA's political wing. "That's not true. We have to do everything we can to stop these things from happening again." Many moderate Basque nationalists share ETA's goal of independence while condemning its terrorist tactics, but even the few people who still support the armed struggle will likely be repulsed by the Madrid carnage.

Even before al-Qaeda claims of responsibility, intelligence experts in Washington saw bin Laden's fingerprints in the wreckage. "There's no doubt in my mind it's al-Qaeda," said a senior FBI counterterrorism veteran. Wherever this investigation leads, the war on terrorism has taken yet another deadly new turn. As a U.S. intelligence official notes, the absence of suicide bombers in Madrid is a sobering development. "You don't have to kill yourself to blow something up," this official says. Since suicide bombers are a finite resource, terrorists could be more inspired than ever to mount devastating attacks by remote control. In other words, Madrid rolled out an innovation that other terrorists will surely copy, says Tarine Fairman, who retired last month as a top international counterterrorism agent at the FBI. "They've introduced a technique that we knew about and were concerned about," he warns, "but are not prepared to deal with."

• Bobby Ghosh and James Graff/Madrid