A bus crash that killed 21 people being transported to a mine in Inner Mongolia is being blamed on brake failure and safety violations. The company whose personnel were killed, Yinman Mining Co., is China’s largest producer of silver, according to the Beijing News.

In addition to the 21 dead, 29 miners and related staff were injured when the bus smashed into the side of a tunnel on Saturday, the semi-official China News Service reported, citing government-affiliated China National Radio.

An investigation by the Emergency Management Ministry found that the bus experienced brake failure and lost control.

It added that the bus, owned by Yinman Mining, was authorized to carry no more than 30 people, but had 50 on board. Yinman Mining also violated regulations that restricted transporting personnel through the tunnel, which should be used to transport equipment, the report said.

The Ministry also blamed lax oversight by local authorities.

Parent company Xingye Mining, which is listed on the Shenzhen Stock Exchange, said in a statement it has suspended Yinman Mining's production and is cooperating with the investigation.

Yinman raked in 398 million yuan ($59 million) in net profit in the first three quarters of last year, accounting for around 70% of its total net profit, Xingye said. If Yinman is forced to cease production for an extended period, it would have a "huge adverse effect” on the company’s fiscal performance in the future, it said.

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