According to news, the West Virginia coal mine disaster

Twenty-five miners are now known to have died and four are missing in an accident at a West Virginia coal mine. The worst mine disaster in the US since 1984 was caused by an underground explosion at Upper Big Branch, about 30 miles south of Charleston. It happened at about 3 p.m. in a chamber 330m below ground, mine owner Massey Energy Company said. The rescue operation has been suspended because rising methane gas levels have heightened the risk of another blast. The operation will resume as soon as conditions allow, Massey Energy said. There are plans to drill holes from the surface to monitor gas levels and attempt to ventilate the mine chamber. A mine safety official said rescue teams had reached one of the mine’s airtight chambers stocked with food, water and oxygen but found no-one there. US President Barack Obama offered his "deepest condolences" to the families and friends of those who had died.