Rescue workers install lights at the entrance of the mine, July 21. [Photo/Xinhua]

HEGANG, Heilongjiang -- A flooded coal mine trapped 15 miners in northeast China's Heilongjiang Province, but local authorities said there is a chance they will survive.

"There's room in the shaft, so survivors are likely," said Wang Kuiyuan, spokesperson for the emergency rescue headquarters in Hegang City, Tuesday night.

But the whereabouts of the trapped miners is still unclear, as the underground geological structure is complicated making search and rescue work progress very slowly, said Wang.

The flood inundated the Xuxiang Colliery in Hegang's Xing'an District at around 5 p.m. on Monday.

Hegang is a major coal producer. Xuxiang Colliery is privately owned, with an annual output of 150,000 tonnes.

Wang said mine production had been suspended for a safety overhaul when the accident happened. "The workers were down there for maintenance instead of mining."

He said the accident was caused by a mud-rock flow, which was the aftermath of recent downpours.

The emergency rescue headquarters worked out two rescue plans Tuesday afternoon. The first involves drilling into the shaft and piping in oxygen and food through the hole, the second excavating into a separate shaft for rescuers to gradually approach the flooded area.

Dozens of electricians have been posted to the site with dynamos to support the rescue operation.