Rescue teams in southern Poland have re-entered a coal mine hoping to find 15 miners trapped deep underground since a gas explosion on Tuesday.

The blast killed eight other miners in the Halemba mine in the city of Ruda Slaska.

Dangerously high levels of methane gas forced emergency workers to retreat from the shaft earlier Wednesday. Polish authorities say search teams recovered six bodies before the threat of new explosions forced them out of the mine. Two other burned corpses were located, but could not be retrieved.

President Lech Kaczynski canceled planned visits to Georgia and Romania to visit the scene of the disaster.

He said one can never lose hope, but he described the situation as very bad.

Some information for this report was provided by AP and Reuters.