British troops accidentally killed four civilians and wounded three others with rockets during an operation against Taliban insurgents in southern Afghanistan, NATO and British officials said Sunday.

The NATO-led International Security Assistance Force said women and children were among the casualties, but it did not detail whether they were dead or wounded.

The British Ministry of Defense said British paratroopers were involved in the episode in the Sangin district of Helmand Province on Saturday. It said the alliance and British forces would investigate.

The alliance force said a patrol had spotted insurgents with weapons preparing to attack from the roof of a compound. “In order to protect themselves,” it said in a statement, the British soldiers “launched three rockets, all of which hit the target. Unbeknown to the patrol, the civilians were inside the compound.”

The force “deeply regrets the tragedy,” the statement added.