KUWAIT -- As investigators looked for al-Qaida links to a deadly attack on U.S. Marines in Kuwait, American forces in that country were involved Wednesday in another violent incident, the second in two days.

A U.S. Army soldier heading to a training area in northern Kuwait fired one shot at a civilian vehicle when one of two people inside the car pointed a gun at the soldiers' Humvee utility vehicle, said a U.S. military official at Camp Doha, an isolated U.S. Army base along the Gulf coast about 12 miles west of Kuwait City. He would not say if anyone was harmed in the incident at 7 p.m., only that U.S. and Kuwaiti authorities were investigating.

U.S. officials in Washington said the shot hit the hood of the civilian vehicle, which then veered off the road. The Americans continued driving to the training area, U.S. officials said.

The Kuwaiti Interior Ministry, which oversees police, initially said it had no information on any such incident -- an indication the civilian car may have driven away.

The violence has startled many in Kuwait, a close U.S. ally where citizens generally consider the United States a friend that liberated their country from Iraqi occupation in the 1991 Gulf war.

Further details also were emerging about the assailants in Tuesday's killing of a U.S. Marine and wounding of a second Marine. The two men, who were shot dead after firing on another group of Marines, were cousins who had fought in Afghanistan, a friend and a relative said Wednesday.

They said the men were angry about Israeli killings of Palestinians and one had made a vague threat about "coming for" Americans.

U.S. and Kuwaiti officials, who are investigating whether the men had links to Osama bin Laden's al-Qaida network, labeled Tuesday's attack an act of terrorism.

Anas al-Kandari, 21, and his 26-year-old cousin, Jassem al-Hajiri, pulled up to a site on Failaka island off the Kuwaiti mainland where U.S. Marines were carrying out urban assault training and opened fire.

Lance Cpl. Antonio J. Sledd, 20, of Hillsbrough, Fla., died soon after. Lance Cpl. George R. Simpson, 21, of Dayton, Ohio, was wounded. His injuries were not life-threatening and he would be flown to a military medical facility in Germany once stable enough to travel.