By 9:00 a.m. Tuesday, four miners are still missing in the ill-fated coal pit of Linjiazhuang Colliery of Lingshi County, Jinzhong City, the emergency rescue headquarters confirmed.

The rescue headquarters said 55 miners, instead of 57 as was previously reported, got trapped when the coal dust explosion went off at 4:40 p.m. last Saturday.

By Tuesday morning, rescuers are able to cross out two lucky miners, Qi Baoyin and Li Xinling, from the casualties.

Qi had left the coal pit to make a phone call shortly before the accident occurred, rescuers said. "When I hang up and reentered the pit, I saw dense smoke and sensed trouble. So I ran away as fast as I could," he said.

He was not immediately seen in the chaos following the tragedy.

Li, the other miner who was crossed out from the casualties, had been hospitalized in the neighboring city of Jiexiu because of an industrial injury since July 7, rescuers confirmed.

The rescue operation is still going on, but high density of carbonic oxide has made it difficult, according to Li Yizhong, head of the State Administration of Work Safety, who is overseeing the rescue work.

Sixty-two miners were working in the pit when the blast went off. Six managed to escape and another one suffering carbon-monoxide poisoning was rescued alive, said An Zhenlu, a local official.

A preliminary investigation shows the coal dust explosion was triggered by an unauthorized explosion in an adjacent mine.

The city government of Jinzhong has launched a crackdown on all illegal mines, urging all mining activities to be performed in line with strict safety rules.