A Qatari man opened fire Wednesday on U.S. and Qatari troops guarding a Qatari air base. The troops were not injured and shot and killed the gunman, both countries said.

No other casualties were reported in the late morning shooting. The attacker's motive was unknown.

The violence at Al-Adid Air Base, which is being used by U.S. military aircraft, came days before Qatar is to play host to world leaders at key trade talks.

Some members of the World Trade Organization had been wary of coming to the Gulf state because of heightened tension in the region linked to U.S. strikes on Afghanistan. Qatar supports the U.S. war on terrorism, and U.S. troops involved in the campaign are in the country.

The gunman fired at a security position manned by two U.S. personnel and a Qatari soldier, said the U.S. Central Command in Tampa, Fla.

The official Qatar News Agency said the gunman fired several times at the air base and that the guards shot back, killing him instantly. It identified the gunman as Abdullah Mubarak al-Hajiri, a Qatari.

In Washington, Pentagon spokeswoman Victoria Clarke declined to answer a question on how many U.S. soldiers or planes might have been at the base at the time.

The air base's security was "never compromised" during the shooting, Central Command said.

Last month, a U.S. master sergeant was killed in a forklift accident while building an air strip in Qatar, becoming the first U.S. casualty linked to the strikes on Afghanistan.

The base is about 60 miles south of the capital, Doha, where the WTO meeting kicks off on Friday.

White House spokesman Ari Fleischer said the shooting did not immediately appear connected to the WTO meeting. "That can change, of course."

The shooting took place several hours before the American WTO delegation was scheduled to arrive at a different military facility, Fleischer said. "The delegation we have sent there landed safely without incident, proceeded to their hotel."

Qatar has been free of the protests that have taken place in other Arab countries against the U.S. military campaign in Afghanistan. President Bush launched the campaign last month after the ruling Taliban militia refused to hand over Usama bin Laden, the prime suspect in the Sept. 11 terrorist attacks that killed about 4,500 people in the United States.

Some WTO officials had suggested moving the meeting out of the volatile Mideast. But the meeting is to go on, and Qatari officials insist their country is prepared and safe.