The last four miners bodies were recovered yesterday at the Upper Branch mine. I think I can just about piece together exactly what happened or at least a close approximation. From what was said by one of the miners who went home to Ohio over the Easter weekend. He knew something was wrong at the mine. "He knew because his April 2 shift had ended about two hours early over ventilation concerns at the mine. He drove to Ohio to spend Easter with his family".
Now I'm guessing here but see if this doesn't fit. The gas alarms started going off sometime in late morning or early afternoon. The crew knew that they were not going to get the problem fixed that day and it being a holiday weekend figured they'd leave it for Monday. I've done this myself in my own profession as in "we're not going to get this fixed everybody clean up and let's get out of here, enjoy your weekend". Now as nobody was going to be in the mine over the weekend they shutdown the ventilation system entirely. That enabled methane over the weekend to fill the entire mine or at least the section where they were working. They fired up the vent fans to part of the mine but weren't able to get the ones working properly in the area of the explosion. The ones that were working provided just the right amount of oxygen so that the gas hit the upper explosion limit. It was just a matter of time before a spark set off the explosion.
I can only hope that something good will come of all of this and they didn't die in vain .