It says they’re US civilians.
http://www.foxnews.com/story/0,2933,581493,00.html?test=latestnews
U.S. Official: 8 Americans Killed in Afghanistan
At least eight American civilians were killed Wednesday after an explosion in eastern Afghanistan.
A U.S. military official told Fox News that the blast occured at Forward Operating Base Chapman in the Khost province. Eight Americans, who were described as civilians and not members of the military, were killed.
A senior U.S. official in Washington said the Americans were killed by an attacker wearing a suicide vest....