Two mine owners were put into police custody Friday in northeast China's coal mine gas explosion that left ten trapped, according to local work safety bureau.

The blast happened at around 5:10 a.m. Thursday in the Baoxing Coal Mine in Fangzheng County, Heilongjiang Province, when 28 miners were carrying out routine tunnel maintaining work. Nineteen escaped while nine others were trapped.

The number of trapped climbed to ten when Zhao Deshuang, a manager of the mine who went down into the mine tunnels to check the situation of the miners after the gas blast, was trapped, the rescue headquarters said on Friday.

Rescuers were struggling to reach the trapped miners, but their rescue efforts has been hampered by the severe flooding that was triggered by the blast, the headquarters said.

Local police has also frozen the assets of the township mine that was co-funded by Cao Bingzheng and Nanmei Group based in Harbin, Heilongjiang's capital.

Cause of the accident is being investigated.

The provincial work safety bureau has closed Baoxing Coal mine and ordered to suspend the production of all other coal mines in Harbin for safety checks.

Thirty-four miners were killed in another colliery gas explosion in the mine on January 11, 2003.