According to a spokesperson for the mining holding group, the mine's monitoring room received alerts of a sudden, dramatic rise in underground gas levels at 1:37 am on Saturday, 53 minutes prior to the tragedy.

The monitoring room immediately cut off underground power and notified all personnel to evacuate, said Zhang Jinguang, publicity chief of the Hegang subsidiary.

Deaths from mining incidents happen often in China. Although work safety situations in China have improved as of late, mine disasters continue to kill people by the thousands each year. Around 3,200 people were killed in 2008.

A State-run mine in Gujiao, Shanxi province, exploded on Feb 22 and killed 77. But in that incident, none of the mine's alarms sounded and, even as gas indicators measured at dangerous levels, nobody at the control room took action.

Xinxing Coal Mine is located around 400 km east of the provincial capital of Harbin and has an approved annual production capacity of 1.45 million tons.

It has an annual coal output of 12 million tons and a verified coal reserve of 3 billion tons.

The Hegang mine incident has already claimed more lives than any disaster of its nature since December 2007, when 105 miners were killed in the coal-rich Shanxi province.

If the eventual death toll exceeds that number, the Hegang incident will have become China's deadliest mine blast since two collieries were flooded in Xintai, Shandong province, in August 2007, killing 181 miners.

Local authorities say a total of 108 "work teams" had been set up to comfort the families of those who were killed or trapped underground.

The families of each deceased miner are expected to receive at least 250,000 yuan ($36,600), 25 percent more than the standard compensation for fatalities in negligent incidents in China.

In quick order, the mine's director, deputy director and chief engineer were sacked on Saturday.