Gunmen ambushed a convoy of election workers on their way to a Taliban (search) stronghold, killing two of them, a senior official said Saturday. One of the attackers was captured.

If confirmed, the casualties would bring to at least 12 the number of people killed while preparing for Afghanistan's first direct presidential vote, set for Oct. 9. Taliban militants have vowed to disrupt the election.

Dozens of militants opened fire on the four jeeps on Friday as they passed through Char Cheno, a district in the central province of Uruzgan, Gov. Jan Mohammed Khan (search) said.

Two members of a team registering voters for the joint Afghan-U.N. electoral commission were killed in a hail of assault-rifle and machine-gun fire, Khan said.

Guards in the convoy shot back, forcing the assailants to retreat into the mountains, Khan said.

One Taliban fighter was captured, Khan said, but gave no further details.

Uruzgan and neighboring Zabul (search) have seen some of the worst fighting in recent months, and attacks have increased as the nation gears up for its first post-Taliban election.

Eight American soldiers were wounded, two of them seriously, in Zabul on Friday when insurgents mounted two attacks with rocket propelled grenades and explosives.

In the first attack on a 10-vehicle convoy, an RPG struck a Humvee, wounding five troops.

Rebels also set off a roadside bomb near Zabul's provincial capital, Qalat, as a U.S. convoy passed. Three soldiers were wounded, but all returned to duty.

Twenty-one American soldiers have died in action this year in Afghanistan, already the worst tally for the U.S. military since it entered the country in 2001.