At least six people have been killed and six others are missing after a bus plunged into a river in northwestern Peru’s Mariscal Luzuriaga province, the country’s health ministry said.

“Six people have died and another six are missing,” said the update from the Peruvian Ministry of Health, in which 15 injured people were taken to a nearby health center.

The causes of the traffic accident, which occurred yesterday Friday, remain unclear so far.

The bus of the company Conchucos Express, in which about 30 people were on board, had left the capital Lima for Pomabamba (north). Under unspecified circumstances, he deviated from his course and fell down a 150-meter cliff, ending up in the river waters.

Road accidents are frequent in Peru and are usually attributed to excessive speed, the poor condition of parts of the road network, as well as a lack of markings and traffic controls.