KUNMING, April 20 -- The death toll from a coal mine flooding in southwest China's Yunnan Province has risen to 21, with another miner still missing, local authorities said Sunday.

The accident took place at Xiahaizi coal mine in Qujing City on April 7, trapping 22 miners underground.

Eleven local officials in charge of work safety have been removed or suspended from their posts, a spokesman with the Qujing municipal government said Sunday.

Previously, seven people, including the board chairman, the legal representative and the manager of the coal mine, have been detained by police.

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

Local authorities are investigating the cause of the accident.