The shootout was sparked when two men on a motorcycle refused to stop when U.S. troops confronted them near Poshakan village in the southern province of Uruzgan province, a hotspot for U.S. troops battling Taliban militants, the local mayor said.

The two men were killed in the fight Wednesday, said Mayor Haji Obaidullah, identifying one of the dead as local Taliban commander Mullah Dur Mohammad.

Obaidullah said Afghan forces arrested another Taliban commander, Mullah Usman, during a search operation on Tuesday in nearby Kalatak village.

The U.S. military said it was involved in a battle in Uruzgan on Wednesday that left one militant dead. It was unclear if it was the same incident. A military statement said patrolling U.S. troops fired back at a man who had shot at them, fatally wounding him. It gave no further details.

The fighting came on the heels of a series of incidents Monday that killed three American soldiers and wounded 14, underlining Afghanistan's fragile security less than three weeks before national elections, which Taliban rebels have vowed to disrupt.

Also Wednesday, three rockets were fired at Bagram Air Base, the hub of U.S. military operations since the war that scattered the Taliban and their al-Qaida allies nearly three years ago.

One of the rockets hit inside the perimeter of the base, injuring a soldier with shrapnel, the statement said. The soldier returned to duty after treatment.

Rockets were fired at U.S. bases in Paktika and Zabul provinces, causing no injuries or damage.

Meanwhile, the U.S. military also said that the first of more than 1,000 extra soldiers assigned to help protect the elections began arriving in Afghanistan on Wednesday.

The troops from the 82nd Airborne Division raise the personnel number in the U.S.-led coalition here to more than 18,000.

NATO (news - web sites) commands a separate 8,000-strong security force to help protect the vote in the country's north.