American officials say three U.S. service members and an Afghan interpreter have been killed in a blast that also left 17 Afghans dead in eastern Afghanistan.

The U.S. Embassy said Wednesday that three NATO service members and an Afghan interpreter died in the explosion. A U.S. official speaking anonymously to discuss casualties ahead of the official release says that the foreign troops killed were Americans.

Afghan officials said the strike in Khost province was a suicide bomber who rammed a vehicle packed with explosives into a military convoy.