Twenty-one workers were trapped underground when water flooded an iron ore mine in east China's Shandong Province Sunday night, the local government said early Monday.

Water flooded a pit of Zhengdong Mining Co. Ltd in Fangzi District of Weifang City at around 11 p.m., when 28 people were working, the city government said in a press release.

Seven people managed to escape, it said.

Rescue work continued Monday. The cause of the accident is under investigation.

This is already the fourth mine disasters in China in 10 days.

In Shandong's Zaozhuang city, 28 coal miners were still trapped after an air compressor caught fire Wednesday.

In the southern Guangxi Zhuang Autonomous Region, rescuers continued to search for 12 workers who were stranded in a coal pit since July 2.

Meanwhile, rescue work has continued for 9 days after a colliery flood trapped 23 workers underground at a pit in Guizhou Province.