Suspected Taliban (search) gunmen ambushed a convoy of civilian trucks carrying vehicles to the U.S. military in southern Afghanistan, killing three drivers, an official said Saturday.

Also Saturday, dozens of Taliban fighters attacked the office of a district chief in southern Afghanistan before dawn, killing three Afghan soldiers, an official said. He said they believe the soldiers also killed about nine rebels.

The attacks were part of a wave of violence that followed a lull during the harsh Afghan winter.

"This shows that some in the Taliban or other anti-government insurgents will continue to try to destabilize Afghanistan through violent acts," said Lt. Cindy Moore, a U.S. spokeswoman. "There is still a threat out there."

The gunmen attacked the trucks Friday after they crossed the Pakistani border at Spin Boldak (search), 55 miles south of Kandahar city, Spin Boldak District Chief Fazeluddin Agha told The Associated Press.

Three drivers — two Pakistanis and one Afghan — were killed in a hail of gunfire that severely damaged the trucks and two of the military vehicles, Agha said. He did not identify the types of vehicles being transported.

The fourth driver escaped and told authorities that four gunmen had appeared in the road in front of the convoy and opened fire, Agha said.

Agha blamed Taliban militants, but provided no evidence. Purported Taliban officials have in the past claimed responsibility for attacks on trucks supplying U.S. bases.

In southern Helmand (search) province, dozens of Taliban attacked a government office in the district of Daisho, 175 miles southwest of Kandahar, triggering a shootout that left three soldiers dead and four wounded, Afghan official Haji Mohammed Rahim said.

"We think our men killed about nine Taliban, but Taliban took their bodies," Rahim said, adding the soldiers had not seen the body of any attackers.

U.S. commanders insist the insurgency is unraveling in the face of American operations and Afghan offers of reconciliation, while warning that a hard core of Taliban militants will fight on more than three years after the hardline militia was ousted for harboring Al Qaeda.

Moore had no information on Friday's incident, but said the "number and severity of attacks" had increased and that the 17,000 U.S. forces in the country would "aggressively pursue those seeking to destabilize the government."