American and Afghan government troops have killed about six insurgents in a battle in central Afghanistan, the US military said. The clash erupted when gunmen fired on what the US military called an offensive patrol in the central province of Uruzgan on Friday. "An estimated six enemy fighters were killed; the remainder fled the area," the US military said in a statement issued late on Friday.The American military, which said no Afghan or US troops had been hurt in the clash, said its offensive patrols were aimed at rooting out insurgents and disrupting supplies. "Such patrols are being conducted through the winter months to deny the enemy sanctuary and hinder the enemy's supply efforts," it said.