A Pakistani official says at least 23 of the country's soldiers were killed in a bus accident in northern Pakistan.

The official says the soldiers were traveling on the bus Saturday when it slid off a road and into a ravine in a mountainous region. Several other people were on board the bus at the time.

The military says the soldiers were on leave going from the Swat Valley to the city of Gilgit.

The cause of the crash is under investigation.