(CNN) — Seven American service members were among the 11 people killed in a helicopter crash in southern Afghanistan on Thursday, NATO’s International Security Assistance Force said.

Three members of the Afghan National Security Forces and an Afghan civilian interpreter also died in the crash of the UH-60 Black Hawk helicopter. The precise location of the crash was not released.

The cause of the crash is under investigation, the ISAF said in a news release.

It comes two days after one of the bloodiest days in Afghanistan so far this year, with three separate attacks leaving at least 47 people dead and at least 145 wounded, according to government and police officials.