KABUL, Afghanistan — Two American service members were killed and two others were wounded in a roadside bomb explosion in southern Afghanistan on Saturday, the United States military command in Afghanistan said in a statement. They were the first American military fatalities in Afghanistan this year.

The victims were in an American military vehicle that struck a roadside bomb in Kandahar Province, where they had been conducting operations as part of the American-led NATO mission known as Resolute Support, according to the statement.

A Taliban spokesman, Qari Yusuf Ahmadi, claimed responsibility for the attack.

The identities of the two killed service members were withheld pending notification of the next of kin. It was not clear which branch of the military they were from.

Twenty American service members were killed in Afghanistan last year. More than 2,400 Americans troops have died in combat since the United States invaded Afghanistan in 2001, according to the website icasualties.org.