Rescue workers try to drain water out of the Haizi colliery of Liming Industry Co. in the Qilin district of Qujing city, Yunnan province on Apr 7, after water started to gush into the mine in the morning, trapping 22 people. [Photo by Zhao Jiarong/ asianewsphoto]

QUJING - Rescuers are racing to pump water from a flooded coal mine in Southwest China's Yunnan province, as all 22 trapped miners remain missing, local authorities said Monday.

As of 4 pm, "the 22 miners were still out of contact" though the water level in the shaft in Qilin District of Qujing city is dropping, said Zhang Lei, deputy head of the rescue headquarters.

Flooding hit the mine at about 4:50 am Monday, when 26 workers were working underground. Four workers were rescued Monday morning.

Local authorities have sent three high-power pumps and more than 500 people to take part in the rescue efforts, said Zhang, also vice mayor of Qujing.

Investigation into the cause of the accident is underway.