At least 27 people were killed and 39 others were injured in Indonesia when a bus plunged into a ravine after its brakes malfunctioned.

The bus was carrying a group of Islamic junior high school students, teachers, and parents from the West Java province town of Subang.

According to a local police officer, the accident happened late night Wednesday on its way back to Subang from a pilgrimage site in the province’s Tasikmalaya district.

The bus plunged into a 20-meter-deep ravine after the driver lost control of the bus.

Authorities are probing the accident but according to the survivors of the incident, brake failure was the apparent cause.

13 of the passengers are being treated for severe injuries, while the rest 26 have minor to moderate injuries.

The Bus driver dies in the accident.