WEST VIRGINIA: An explosion at a remote coal mine in southern West Virginia with a history of safety problems killed 25 workers today, while at least four were still missing.

Rescuers had been making their way to the area where the miners were trapped at Massey Energy Co’s sprawling Upper Big Branch mine, where

the blast occurred around

3 pm yesterday.

Earlier, Kevin Stricklin,

an administrator for the federal Mine Safety and Health Administration,

said officials hoped some

of the missing had survived the initial blast and

were able to reach airtight chambers stocked with food, water and enough oxygen for them to live

for four days. However, rescue teams made it to one of two nearby shelters and it was empty. The gas levels prevented them from reaching the second.

Massey Energy and safety officials confirmed that 25 bodies were found. “It does not appear that any of the individuals made it to a rescue chamber,” Stricklin said at a news conference.

It was the worst mine disaster since 1984 when 27 were killed by a fire at Emery Mining Corp’s mine in Orangeville, Utah.

Though the cause of the blast was not known, the operation about 48 km south of Charleston has a history of violations for not properly ventilating highly combustible methane gas, safety officials said.

Massey Energy, a publicly traded company based in Richmond, Virginia, has 2.2 billion tonnes of coal reserves in southern West Virginia, eastern Kentucky, southwest Virginia and Tennessee, according to the company’s Web site. It ranks among the top five US coal producers and is among the industry’s most profitable.

In the past year, federal inspectors have fined the company more than $382,000 for repeated serious violations involving its ventilation plan and equipment at Upper Big Branch, which is run by subsidiary Performance Coal Co. The violations also cover failing to follow the plan, allowing combustible coal dust to pile up, and having improper firefighting equipment.

Federal and state regulators have required mine operators to store extra oxygen supplies. Upper Big Branch uses containers that can generate about an hour of breathable air, and all miners carry a container on their belts besides the stockpiles inside the mine.

Rescuers trying to reach the trapped miners had found evidence that

some workers took emergency oxygen supplies

from a cache in the mine, Stricklin said.