President Clinton sent a four-man FBI anti-terrorism team to Pakistan to investigate the killings today of two U.S. diplomats in Karachi. The Americans, consulate staff members Jackie Van Landingham and Gary Durell, were on their way to work this morning in a van with U.S. markings when two gunmen jumped out of a yellow taxi, spraying the van with automatic gunfire. A third consulate employee in the van was wounded. Pakistani Prime Minister Benazir Bhutto said it was "part of a well-planned campaign of terrorism," possibly retaliation for the arrest in Pakistan last month of Ramzi Yousef, an Iraqi-born resident of Kuwait and a chief suspect in theWorld Trade Center bombingin New York. But State Department and other government sources tell TIME Washington correspondent Douglas Waller they're not so sure. "Karachi is like the Wild West," says Waller. "It's just riven with political and ethnic factions." Over the last 15 months, he says, groups with varying motives have killed more than 1,000 Pakistanis and foreigners.