President Hamid Karzai condemned the use of gunfire by US troops to suppress Afghans angered by a traffic accident involving a military truck that sparked the worst riots in the capital since the fall of the Taliban. Speaking in his native Pashto language, Karzai used phrases that left open whether the US troops had fired into a crowd that had gathered at the scene of Monday's accident, or only over their heads. But he was strongly critical. "The coalition opened fire, and we strongly condemn that," Karzai said Thursday in a national radio address. "I have to say, all the time we tell them to be careful because we have one joint aim, which is the struggle against terrorism." Afghan authorities and the US military are investigating the crash in which a US truck that the military says suffered brake failure rammed into cars at an intersection, killing up to five people.