Rebels killed seven police officers and abducted two after ambushing them on a road in southern Afghanistan, while two villagers were abducted and beheaded, officials said Thursday.

Two U.S. soldiers, meanwhile, were wounded when an Afghan army officer opened fire on them at a joint base in eastern Paktia province Wednesday, Gen. Rahmatullah Raofi said. The American forces returned fire and killed the Afghan officer.

He said it was not immediately clear why the officer fired at the troops. A U.S. military spokesman in Kabul said he had no information on the incident.

The police were driving in three vehicles on a road toward Kandahar, the former Taliban stronghold in southern Afghanistan, when they were attacked Wednesday in Shah Wali Kot district, said Jan Mohammed Khan, a local governor.

Police in one of the vehicles fought back and managed to flee, but the two other vehicles were hit by rockets, he said.

The attack was the latest in a string of assaults recently on the fledgling police force in southern Afghanistan.

The two villagers who were beheaded were abducted by suspected Taliban rebels in southern Uruzgan province on Monday, Khan said. Their bodies were discovered Wednesday.

He said the Taliban mistakenly believed the men were working as interpreters for U.S.-led coalition forces.

The governor said security forces rushed to the area and raided a rebel camp, arresting a district insurgent commander and another fighter.

Taliban-led rebels have stepped up attacks across southern and eastern Afghanistan this year, leaving about 1,500 people dead and much of the area off-limits to aid workers.