A bus in north-central China’s Shaanxi province fell off a cliff on Friday and killed at least 35 passengers. The reason behind the crash was not immediately known, but authorities are investigating the incident.

Of the casualties, 25 people died instantly, while 10 died in the hospital where they were being treated for injuries. The bus was carrying 46 passengers when the accident occurred, Xinhua reported. Another 11 people were being treated at the hospital.

The bus reportedly fell over 30 meters into a deep forest.

The country has been hit with several road accidents in the recent past due to lack of safety measures and overcrowded vehicles. In February, the driver of a minibus in southern China lost control of the vehicle with 13 people on board, while negotiating a sharp turn and went downhill an expressway.

Last July, at least 38 people were killed after a truck with flammable liquid crashed into a bus carrying 53 people in the central Hunan province. In June last year, a school van carrying 11 people, including eight children, sank into a pond in Hunan.