At least 13 people were killed after a bus with 36 passengers fell into a valley in Northwest China's Xinjiang Uygur autonomous region on Tuesday afternoon.

The accident happened at around 5:15 pm in an area with an average altitude of 2,000 meters near Miaoergou village, in the Changji Hui autonomous prefecture. The passengers were employees of a local company who were returning after touring an attraction near the village, the Xinjiang information office said on Tuesday evening.

The bus, which was not overloaded, rolled over and fell about 40 meters into the valley. The road on which it was traveling was wet and muddy because it had rained during the day, the Changji public security bureau said. According to initial investigations, mist and poor visibility might be partly to blame for the accident.