Four people died and 12 others are missing after a construction cable broke at around 3am Friday at a bridge under construction on the Qinghai section of the Sichuan-Qinghai Railway, according to the respective department in northwest China's Qinghai Province, Xinhua reports.

Search and rescue efforts are underway.

The bridge being built over the Yellow River is a steel truss arch construction. Its main span was expected to be closed by the end of this month.