Eighteen people were killed and 31 others injured on Saturday when a bus fell into a 250-meter- deep ravine and broke into two parts at kilometer 40 of the La Rumorosa highway, in northern Mexico state, Baja California.

Three children were killed and five children were injured in the accident, Afredo Escobedo Ortiz, the head of the state government's civil protection department told media.

Mexican media named 14 of the dead and said that four people remain unidentified. Those named are between 3 and 26 years old. Earlier reports said that only 14 people had died.

Regional authorities said that brake failure was the most likely cause. Involved in the rescue work are police and fire crews from the cities of Tecate, Tijuana and Mexicali, all in Baja California. The dead and injured are being taken to Mexicali.

On Thursday, a researcher at the National Autonomous University of Mexico, told reporters that road accidents kill around 15,000 people in Mexico each year, due to poor road quality and dilapidated vehicles. He estimated that 80 percent of Mexico's deadly accidents are preventable.