An explosion at a remote coal mine with a history of safety problems killed 25 workers and at least four others were still missing early Tuesday more than a thousand feet underground in the worst U.S. mine disaster since 1984.
Though the cause of the blast was not known, Massey Energy's sprawling Upper Big Branch mine has a history of violations for not properly ventilating highly combustible methane gas, safety officials said.
Nine miners were leaving on a vehicle that takes them in and out of the long shaft, when a crew ahead of the them felt a blast of air and went back to investigate, said Kevin Stricklin, an administrator for the federal Mine Safety and Health Administration (MSHA).
They found nine workers, seven of whom were dead. Two others were injured. Two other nine-person crews and a safety inspector who had been working alone were believed trapped, perhaps about a mile and a half underground, said Stricklin, Seattle Times reported.
According to Los Angeles Times, the explosion about 3 p.m. Monday had disabled communication lines, including wireless systems, inside the vast underground complex, officials said.
Officials had raised hopes during the day that many of the missing miners might have used emergency escape routes to reach specially reinforced, airtight chambers that are stocked with food, water and air about a mile and a half below the Earth's surface. If so, the sites could sustain them for several days.
Officials said they didn't yet know the cause of Monday's deadly accident at the mine, which is owned by Massey Energy Co., one of the nation's largest coal producers. But federal mine safety and health officials have cited the mine owner and operator repeatedly for potentially dangerous conditions, at the mine, including venting of combustible methane gas.