An explosion Monday at a coal mine owned by Massey Energy has left 25 confirmed dead and four missing as of Wednesday morning.

Mine Safety Health Administration (MSHA) rescue efforts continue at the Upper Big Branch mine in Montcoal, West Virginia, but The Wall Street Journal quoted Massey Energy Co. Chief Executive Don Blankenship as saying, "The explosion was very violent, so their chances of survival are very low." 
Though the cause of the explosion has not been determined, MSHA Administrator Kevin Stricklin has commented that all signs point to a buildup of methane. This particular mine has a history of citations involving the ventilation of the gas.
Several media reports have noted that Massey has been repeatedly cited for safety violations over the years and that the Upper Big Branch mine has been cited more than 3,000 times since 1995 for safety violations. So far this year, it has received 10 citations regarding the ventilation of methane and coal dust. Stricklin was quoted as saying, "An explosion wouldn’t have happened if it was operating safely."

Early Wednesday morning, rescue teams completed drilling the first hole to vent toxic gas from the mine shaft near where they think the remaining miners would have sought safety. When they banged on the drill pipe, there was no response.

Massey is the sixth-largest U.S. coal producer. Monday’s disaster was the deadliest U.S. mine incident in a quarter century.

China also recently experienced multiple deadly coal mine disasters. At least nine miners died as a result of flooding March 28 at a mine in northern China, and 40 were confirmed dead as the result of an explosion last week at a central China mine that is said to have been operating illegally. Most recently, China Daily reported that one person was confirmed dead and another two were missing after a coal dust fire Wednesday morning at a privately owned mine in southwestern China’s Yunnan Province. The Chinese government is reported to be initiating a nationwide effort to deal with safety violations.

Sources: MSHA, Wall Street Journal, NBC, Marketwatch, China Daily