The Pakistani army has confirmed that three U.S. military personnel were killed and another wounded in an attack today in northwest Pakistan, the Associated Press reports.

According to the BBC, the three Americans were U.S. Marines and another seven people also died. The Americans were in a convoy was headed to the inauguration of a school for girls when there was an explosion as they passed another school. At least 70 people, 63 of them girls, were wounded, the BBC adds.

Update at 9:30 a.m. ET. From Islamabad, NPR's Julie McCarthy reports that two Americans were injured, and that:

In a statement the U.S. embassy said those killed were U.S. military personnel who were in Pakistan to conduct training at the invitation of the Pakistan Frontier Corps.

The five Americans were traveling in a security convoy when their bullet-proof vehicle was struck. The Commandant of the Dir Scouts who was traveling in the convoy told NPR that a suicide attacker detonated his bomb-laden car as the convoy passed.

The area is a militant stronghold, but the Pakistani army has insisted it had been cleared. The embassy said the U.S. personnel were in Lower Dir to attend the inauguration of a school for girls that had been recently renovated with U.S. humanitarian assistance. The deadly explosion occurred near another girls' school, and claimed the lives of three young students, carnage the Embassy said "clearly shows the terrorists vision."

Update at 8:05 a.m. ET: CNN says it has been told by sources that the three Americans were members of the Special Forces.