At least 12 people died, and four remain missing after a steel cable snapped during bridge construction in northwest China's Qinghai Province on Friday, media reports said.

The accident occurred at the site of the bridge under construction on the Qinghai section of the Sichuan-Qinghai Railway in Jainca County, Huangnan Tibetan Autonomous Prefecture, at around 3.10 am.

The failure caused a 108-meter steel girder arch rib to collapse, with 16 workers present at the site at the time of the accident, Xinhua reported.

806 personnel, supported by 91 vehicles, 27 boats, one helicopter and five robots, are participating in the rescue operation.

Six local hospitals have opened green channels for medical treatment.

The Ministry of Emergency Management said the cause of the accident should be identified as soon as possible and efforts should be made to resolutely prevent similar accidents, Xinhua reported.