Mexico police and volunteers pull bus back upright after crash kills at least 27

At least 27 people were killed in Mexico when a passenger bus careened off a mountain road and plummeted into a ravine Wednesday in the southern state of Oaxaca, police said."

According to a preliminary toll, 27 people died and 17 injured were transferred to different hospitals in the region for medical attention," Oaxaca state prosecutor told AFP.An investigation has been launched into the cause of the accident, with early indications suggesting mechanical failure, he added.At least six of the injured were unconscious and in serious condition when they were rushed to hospital, according to the civil protection agency.

The bus, operated by a local transport company, had left the capital Mexico City on Tuesday night and was heading for the town of Santiago de Yosondua."The driver of the vehicle presumably lost control... and unfortunately it fell into a ravine more than 25 meters deep," a state official said.Deadly road accidents are common in Mexico, usually due to high speeds, poor vehicle conditions or driver fatigue.