Two U.S. service members were killed and two others injured when their vehicle was hit by a roadside bomb in southern Afghanistan, the U.S. military said in a statement Saturday. The Taliban immediately took responsibility for the attack.

Qari Yusouf Ahmadi, a Taliban spokesman, said it occurred in the southern Kandahar province.

In keeping with defense department rules, the U.S. military did not identify the service members.

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More than 2,400 U.S. service members have been killed in Afghanistan. Last year was one of the deadliest even as the United States engaged in peace talks with the Taliban insurgents, who immediately took responsibility for the attack.

Earlier, both NATO and Afghan officials had confirmed a roadside bomb hit a U.S. army vehicle Saturday, without mentioning casualties. In a short statement, a NATO spokesman said that officials were still "assessing the situation and will provide more information as it became available."

An Afghan official said the attack had taken place in the Dand district of Kandahar province. The official was not authorized to speak with media and requested anonymity.

The Taliban now control or hold sway over roughly half of Afghanistan. The militants continue to stage near-daily attacks targeting Afghan and U.S. forces, even as they hold peace talks with the U.S. Scores of Afghan civilians are also killed in the crossfire or by roadside bombs planted by militants.

In November, two U.S. service members were killed when their helicopter crashed in eastern Logar province. The U.S. military at the time said preliminary reports did not indicate it was caused by enemy fire, though the Taliban claimed to have shot down the helicopter - a claim the U.S military dismissed as false.

U.S. Ambassador John Bass left Kabul last week, ending his two-year tenure as America's top diplomat.