US troops in Iraq shot dead four detainees on Monday during a riot at the main US prison camp for guerrilla suspects, near the Kuwaiti border while a final vote count cast began on Tuesday at the national centre for the Iraqi elections. The final results were not expected for at least another week, the independent electoral commission announced. US officers said six prisoners were also wounded in the violence, which affected hundreds of men at Camp Bucca on the day after Iraqis voted in their first free election in decades. There were no serious injuries among the Americans during 45 minutes of rioting, Lt Col Barry Johnson said. Troops shot the four dead with rifles after failing to quell rock-throwing rioters with plastic pellets fired from shotguns. "We're not sure exactly what sparked it. There's no obvious connection with the election. We're not sure if that had anything to do with it," Johnson, a spokesman for the US military detentions operation in Iraq, said.