Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. West Virginia Coal Mine Explosion Kills 12 06 April 2010 Emergency vehicles near the mine site in West Virginia Emergency vehicles near the mine site in West Virginia At least 12 coal miners are reported dead and several others are missing after an explosion at amine in the eastern U.S. state of West Virginia. Federal mine safety official Kevin Stricklin said rescue workers were working hard early Tuesday to reach the area far below ground where at least 10 workers were trapped. Stricklin said the workers were probably more than two kilometers underground. He said the rescue team was hopeful the workers had reached one of the airtight safety chambers stocked with enough food, water and oxygen to last four days. The blast happened Monday afternoon at Massey Energy's Upper Big Branch South mine in Raleigh County, about 50 kilometers from Charleston, the state capital. The cause of the explosion has yet to be determined. But mine safety experts say it could have been the result of a methane gas buildup in the shaft. Methane gas is highly flammable and is frequently found in coal mines. The mine has had a spotty safety record, with a higher than average injury rate. Massey Energy chief Don Blankenship said safety is a priority for the company and they were working hard to rescue to remaining trapped miners. Stricklin said the explosion occurred as workers were traveling up a mineshaft to exit the mine. A second group, farther up, said they felt a blast of air. They went back to investigate and found nine workers, seven of whom were already dead. It is not clear what the situation was further down the mine, where the other miners were at work. State Governor Joe Manchin, who was away on a personal trip, is returning home. West Virginia is also where 12 miners died after an explosion in the Sago coal mine in January 2006. That accident trapped 13 men underground for two days. One miner survived, while the rest died of carbon monoxide poisoning. Some information for this report provided by AP, AFP and Reuters. .