KABUL, Afghanistan - U.S. troops opened fire on a bus carrying civilians in Afghanistan, killing four passengers after their driver failed to stop.
A spokesman for NATO's International Security Assistance Force said the bus was heading toward 20 troops on foot patrol on a highway in central Wardak province on Friday.
The troops first fired warning rounds into the air to stop the vehicle, then shot into the engine block.
The bus kept coming, so they opened fire on the vehicle.
The provincial governor and area residents confirmed that the troops were U.S. forces.
The incident is one of a series that threaten to undermine Afghan support for foreign troops just as the United States prepares to boost its presence in the country.
The UN said in September that 577 Afghan civilians had been killed this year by U.S., NATO and Afghan troops, a 21 per cent jump from 2007.
Taliban fighters and other insurgents killed another 800 civilians this year.
The bullet-riddled bus had been moved to the side of the road by the afternoon, and U.S. troops cordoned off the area, according to an AP cameraman on the scene.
U.S. forces spokesmen declined to comment on the incident, referring all inquiries to NATO's International Security Assistance Force because the troops were operating under its auspices.
The shooting occurred about 65 kilometres south of Kabul on the main road between the capital and the southern city of Kandahar.
