NANNING - Three workers were trapped by flood while prospecting for an iron mine in South China's Guangxi Zhuang autonomous region Saturday night, the local safety watchdog said Sunday.

The accident happened at 8:50 p.m. in a village in Yunbiao Township, Hengxian County, the work safety bureau in the regional capital Nanning said in a press release.

Of the five people working underground, two escaped without injuries, it said.

Neither of the two survivors was immediately available for an interview.

Rescue work continued Sunday, and the cause of the accident was under investigation.

A work safety bureau official said the prospecting operation was legal and had been authorized.

The area was believed to have rich iron, copper and gold reserves, he said.