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. US Rescuers Forced to Evacuate W. Virginia Mine VOA News 08 April 2010 Kevin Stricklin (R), an administrator with Mine Safety and Health Administration, speaks during a press conference near Upper Big Branch coal mine in Montcoal, West Virginia, 08 Apr 2010 Photo: AFP Kevin Stricklin (R), an administrator with Mine Safety and Health Administration, speaks during a press conference near Upper Big Branch coal mine in Montcoal, West Virginia, 08 Apr 2010, three days after an explosion killed 25 miners Officials in the mountainous eastern U.S. state of West Virginia have evacuated a rescue team from a coal mine where an explosion killed 25 people on Monday. Mine safety official Kevin Stricklin said Thursday that rescue teams searching for four missing miners encountered a "setback" because of a dangerous build-up of toxic gases. He said rescuers were in danger and were leaving their equipment behind to return to the surface. About 32 workers with gas masks entered the mine early Thursday to begin an eight kilometer trek through Massey Energy Company's Upper Big Branch Mine.  The rescuers are trying to reach a chamber about 300 meters underground, where they believe the missing miners are located. Officials say they are hoping against the odds that the men survived the powerful blast and reached an airtight rescue chamber. Rescuers banged on pipes Wednesday, but have heard no signs of life in the mine since the blast. High levels of methane and carbon monoxide gases in the mine have hampered rescue efforts since Tuesday. Officials say a build-up of methane gas most likely caused the blast. The gas is highly flammable and frequently found in coal mines. Federal officials say they will fully investigate a lengthy record of safety violations by Massey Energy. The company was fined $900,000 last year for violations at this one mine. This is the deadliest mine accident in the U.S. since 1984, when 27 workers were killed in a fire in Utah. .