KUNMING, April 18 -- The death toll from a mine flood in southwest China's Yunnan Province rose to 20 by 7 p.m. Friday as rescuers found 14 more bodies, with two others still missing.

The accident, which happened at 4:50 a.m. on April 7 at Xiahaizi coal mine in Qujing City, trapping 22 miners underground, while four others were rescued, according to the rescue headquarters.

Seven people involved in the accident including the board chairman, the legal representative and the manager of the coal mine have been detained by police.

Investigators believe the flooding was caused by an explosion.

Narrow underground space and complicated layout of the mine have hampered search efforts.

Rescuers are continuing to search for the two miners.