KABUL, Afghanistan — American troops opened fire after a roadside bomb hit their convoy in Afghanistan’s Nangarhar province on Monday, killing three civilians, a spokesman for the provincial government claimed.

“After the explosion, the foreign forces started shooting and killed a man and his two sons,” Attaullah Khogyani said.

U.S. Forces-Afghanistan confirmed that a convoy of American and Afghan personnel had been struck by a bomb and small arms fire in the area before it returned fire in self defense.

However, a statement said it had not received any “official allegations” of civilian casualties, and that an investigation into the incident had been launched.