Eighteen people are dead and 13 others injured after a bus crashed through a guard rail on a mountain road and plunged 40 meters into a stream on Tuesday.

Police fear the death toll will rise, noting that most of the injured are in critical condition.

The accident occurred in front of the entrance to Mount Cheongnyang in Bonghwa County, North Gyeongsang Province at around 3:45 in the afternoon, Korean time.

Police said that the 30 female passengers were members of a hiking club.

Police believe the crash was caused by either a brake malfunction or a flat tire, but did not preclude the possibility of carelessness on the part of the driver, who is among the injured.