WASHINGTON — A Pentagon official said a U.S. soldier killed five fellow troops at American base in Baghdad.

The five were killed in a shooting this afternoon, Baghdad time, at Camp Liberty near Baghdad International.

A senior military official in Washington said he has no other details on what happened. He spoke on condition of anonymity because the circumstances surrounding the deaths are under investigation.

The toll was the highest for U.S. personnel in a single incident since April 10, when a suicide truck driver killed five American soldiers with a blast near a police headquarters in the northern city of Mosul.