At least 20 killed in bus accident at China mine State media report at least 20 people were killed and 30 injured in a bus accident blamed on faulty brakes at a mine in northern China

BEIJING -- At least 20 people were killed Saturday and 30 injured in a bus accident blamed on faulty brakes at a mine in northern China, state media reported.

The accident occurred at a lead, zinc and silver mine operated by the Yinman Mining Co. in the sprawling inner Mongolia region, the Xinhua News Agency said.

The casualties occurred when a bus carrying 50 miners to the underground operation went out of control and crashed into the side of the tunnel, Xinhua said.

A working team from the Ministry of Emergency Management has sent a working team to "guide and assist" in the rescue and investigation at the accident site, the report said.

Executives of the company have been placed under travel restrictions while the investigation is underway, it said.

Despite huge safety improvements in recent years, scores of Chinese miners die each year, largely in gas explosions, underground floods and collapses due to structural defects.