Fort Bragg, N.C. — Three soldiers based at Fort Bragg died Wednesday when a roadside bomb went off in northwest Pakistan, the Department of Defense announced Friday.

Sgt. 1st Class David J. Hartman, 27, of Okinawa, Japan, and Sgt. 1st Class Matthew S. Sluss-Tiller, 35, of Callettsburg, Ky. , were assigned to the 96th Civil Affairs Battalion (Airborne), 95th Civil Affairs Brigade (Airborne). Staff Sgt. Mark A. Stets, 39, of El Cajon, Calif., was assigned to the 8th Psychological Operations Battalion (Airborne), 4th Psychological Operations Group (Airborne).

The blast, which flattened a nearby school, also killed three schoolgirls and a Pakistani soldier who was traveling with the Americans.

The soldiers were in the region as part of a U.S. mission to train members of the paramilitary Frontier Corps, Pakistan's army and the U.S. Embassy said. They were the first known U.S. military fatalities in Pakistan's lawless tribal regions near the Afghan border, officials said.

Their deaths bring the number of Fort Bragg soldiers killed in action in the last week to seven. Two were killed last Friday in Wardak province of Afghanistan while supporting combat operations, and two others died when the vehicle they were driving struck an improvised explosive device in Afghanistan's Zabul province on Tuesday.