Thirteen miners at an Upshur County coal mine may not have begun the process of re-starting electrical mining equipment before a Monday morning explosion that trapped them deep inside the operation, the federal mine safety official running the rescue operation said Tuesday.If correct, that conclusion — a very preliminary estimate based on quick interviews with miners who escaped the Sago Mine — would remove one potential source of the spark that ignited the blast.“We don’t think they made it to the [coal] face,” said Kevin Stricklin, district manager for the U.S. Mine Safety and Health Administration.The Sago Mine had been closed from early Saturday morning until a Monday day shift came to work.Two groups of miners entered on man-trip vehicles, splitting up when they reached tunnels that headed for separate mining faces.The rear group heard the explosion and escaped. The first group of 13 miners did not make it out.Stricklin said that his agency’s current estimated timeline would not have given the first group time to re-start equipment that was off during the holiday shutdown.“It doesn’t sound like they did much of anything,” Stricklin said in a phone interview. “I’m pretty confident that they weren’t mining any coal.”Stricklin and other mine safety experts cautioned against drawing too much from earlier bits of information about the blast at International Coal Group’s Sago Mine.“We do not know what caused this explosion,” company President Ben Hatfield told reporters at a late afternoon briefing.A detailed and complicated investigation will be needed to pinpoint what caused the blast. That process will not even start until the ongoing rescue efforts are completed.Gov. Joe Manchin has promised a comprehensive state probe. MSHA will do its own investigation, probably to be run by agency experts from a different district office.Generally, all coal mines contain two major sources of explosions: Methane gas and coal dust.Some experts believe that Monday’s blast was caused by coal dust. They note that it was powerful enough to blow out some “stoppings,” internal mine walls — usually made of concrete blocks — that are used to control air flow. Dust explosions are often much more powerful than methane blasts.Explosions can be triggered from any number of ignition sources, from cigarettes to sparks from mining equipment.Winter months are dangerous. Low barometric pressure and humidity, coupled with seasonal drying, make conditions ripe for explosions.Drier air allows for the suspension of coal dust in the atmosphere, increasing the chance of a blast. Low pressure allows methane to move more easily into active areas, where it can possibly ignite.Early on Monday, Manchin’s press spokeswoman, Lara Ramsburg, was passing on reports that lightning may have sparked the Sago Mine explosion.If that turns out to be the case, it would not be the first time that a major mining accident in West Virginia was traced to lightning.On June 28, 1986, lightning set off a premature dynamite explosion at BethEnergy’s High Power Energy strip mine in Nicholas County. Two cousins, Randall Roop, 35, of Drennen, and Michael Roop, 39, of Belva, were killed.In a report on that accident, MSHA concluded that the deaths occurred, “when the victims who knew an electrical storm was present failed to comply with known company policy and federal regulations which require all persons to be withdrawn to a safe location away from the blast area during an electrical storm.”Lightning has also been known to cause underground mine explosions, especially in worked-out, sealed mines. Lightning can strike metal equipment on the surface and ignite methane underground.Three such explosions occurred between 1994 and 1996 in Alabama, according to a 2001 report from the National Institute for Occupational Safety and Health.MSHA officials would not speculate about whether lightning played a role in the Sago Mine explosion. “Anything is possible right now,” Stricklin said.Company officials were at a loss.Gene Kitts, a company vice president and mining engineer, told reporters that a fire boss did required mine safety checks just before the shift Monday morning.“That just adds to the mystery of how this happened,” Kitts said. “It was inspected as required by the regulations and it was clean, and an hour later, there was this explosion.”To contact staff writer Ken Ward Jr., use e-mail or call 348-1702.