At least 11 are dead after a mini-bus carrying 27 people veered off a road and plunged into a ravine in northwest China's Ningxia Hui Autonomous Region Saturday morning, local authorities said.

All of the 27 were rushed to the local hospital, but 11 died after emergency treatment failed, said rescuers.

Qiu Guodong, head of the fire squad in Haiyuan County which carried out the rescue work, said the accident happened at 7:43 a.m. Saturday when the bus hurtled off a mountain road in Haiyuan, plunging more than 20 meters into the ravine.

An investigation into the accident is under way, said Qiu.