A U.S. soldier and a former Afghan militia leader were killed Sunday when American troops clashed with gunmen during a search operation in western Afghanistan, U.S. and Afghan officials said.

The troops came under attack from "an unknown number of enemy forces" while searching a compound near Shindand Airfield (search) in Herat province (search) and returned fire, a U.S. military statement said.

"The Afghan citizen died at the scene," the statement said. "The U.S. soldier was wounded in the attack and ... died a short time later at the airfield."

The soldier's name was being withheld until his next of kin could be notified.

The military also didn't identify the dead Afghan, or say if he was a suspected militant or a bystander.

But a local militia commander, Akhtar Mohammed Husseini, said the compound belonged to a former militia leader called Mullah Dost.

"There was fire from both sides. Mullah Dost was killed along with his wife, and two of their children were injured," Husseini told The Associated Press by telephone. "The Americans wanted to search his house, but we don't know who fired first."

Ziauddin Mahmoudi, the provincial police chief, gave a slightly different account, saying Dost and one of his daughters were killed in the pre-dawn fight.

Mahmoudi said Dost was a veteran of Afghanistan's war against Soviet occupation in the 1980s who later aligned with the Taliban. He said Dost also served briefly as police chief in Shindand district last year.

U.S. military spokesman Maj. Mark McCann said he had information about only two fatalities but no further details.

The dead soldier was the first U.S. combat casualty this year and at least the 117th here since Enduring Freedom, America's anti-terrorism operation, began in late 2001.

It was also the first since the start of Operation Lightning Freedom, the latest phase of the American military operation in Afghanistan, begun after Hamid Karzai's inauguration as the country's first directly elected president in early December.

U.S. and Afghan government forces have been stationed at Shindand Airfield, 400 miles west of the capital, Kabul, since intervening to halt bloody factional fighting in the region near the Iranian border in August.

Dozens of Afghan militiamen were killed in the battles, which resulted in the ouster of local strongman Ismail Khan as governor of Herat province. There were no American victims.

McCann said Sunday's "routine" search was part of the military's effort to create a stable environment for parliamentary elections expected to take place in April or May.