The US State Department confirmed Wednesday the death of eight Americans in a suicide blast in Afghanistan.

Department Spokesperson Ian Kelly said the eight died in an attack at the Forward Operating Base Chapman in Khost province, southern Afghanistan.

However, Kelly didn't say whether those killed were military personnel or civilians, saying the department is "withholding further details pending notification of next of kin."

Reports have indicated the killed were civilians, possibly contractors working with the military.

The attack occurred during the afternoon when an attacker wearing a suicide vest detonated the explosive device.