A gas explosion at a coal mine on Saturday in Central China's Henan Province killed 18 workers and injured 20 by yesterday.

The blast occurred at about 5 pm, at the Sundian Coal Mine of Datun Twon, Ruzhou City, when workers were changing shifts beneath the shaft.

"The explosion was very unexpected. I passed out for half an hour after it," said Zhang, one of the injured workers.

The cause of the explosion was still unknown yesterday, said local officials who refused to speak in detail about the tragedy.

But the State Administration for Safe Production Supervision said the site has been cleaned up and all of the workers found.

Five managers in charge of safety, machinery and maintenance at the mine were taken in for questioning by local police, said local sources.

The coal mine is a privately-owned joint venture, with a legal licence.

Shi Jichun, vice-governor of the province, has ordered the Henan Coal Industry Bureau, Henan Administration for Safe Production Supervision, and other related departments to deal with the aftermath of the event.

The gas in the mine is mixed with carbon matters that have a large composition of methane (marsh gas).

The gas is lighter than air, inflammable and explosive. It has caused other coal mine explosions.

When the gas is concentrated and it meets a fire starting agent, explosions happen, said experts.

The injured workers were sent to Ruzhou Orthopaedics Hospital for emergency treatment immediately after the explosion. Doctors at the hospital are still treating them.

(China Daily November 25, 2003)