WASHINGTON -- An American service member was killed in eastern Afghanistan on Thursday, the second U.S. military death in Afghanistan in less than a week. Officials said the service member died of a wound sustained in a combat operation.

The service member's identity was being withheld pending notification of family members. The military said one Afghan security force member also was killed and several were wounded in Thursday's incident.

Thursday's death marked the fourth American servicemember to be killed in Afghanistan this year. On Jan. 1, Army Sgt. 1st Class Mihail Golin, 34, of Fort Lee, New Jersey, was killed in fighting in Nangarhar province, and on April 30, Army Spc. Gabriel D. Conde, 22, of Loveland, Colorado, was killed in Kapisa province.

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On Saturday, Army Cpl. Joseph Maciel, of South Gate, California, was killed by what the U.S. is investigating as a possible attack by a member of the Afghan military.

The U.S. has about 15,000 troops in Afghanistan. In addition to supporting Afghan forces fighting the Taliban, U.S. forces are combating extremist groups in eastern Afghanistan, mainly the Islamic State of Iraq and Syria's Afghanistan affiliate in the province of Nangarhar.