Taliban gunmen have raided a police post near an Afghan hydro-power dam and killed six policemen.
The Kajaki Dam, which supplies power to southern Afghanistan's main city, Kandahar, was not damaged in the late-night attack, said a spokesman for the governor of Helmand province, where the dam is located.
One Taliban fighter was killed and two wounded when police returned fire, he said.
Taliban fighters opposed to Afghanistan's US-backed government and the presence of foreign forces have tried to attack the Kajaki Dam before.
Part of the hydro-power system was damaged in US bombing in late 2001, launched after the then ruling Taliban refused to hand over Osama bin Laden and other al-Qaeda leaders.
The Taliban were ousted in November 2001 and have been waging a guerrilla insurgency ever since, particularly in the south and east of the country.