The desperate families of West Virginia miners still unaccounted for were told late today that holes drilled into the exploded mine shaft were beginning to help release the toxic gases that have kept rescue teams from going in to search for survivors.
A federal safety official said this evening that levels of carbon monoxide, hydrogen and methane were dropping at the top of the holes and levels at the bottom of the holes would be tested late this evening to determine whether it was safe for rescuers to go into the mine.
"The one thing that looks positive to us is we're seeing a downward trend and that's a positive thing," said Kevin Stricklin, an administrator from the federal Mine Safety and Health Administration. "We just want to make sure that downward trend isn't deluded."
He said rescuers could go into the mine overnight if it is determined that the air is safe.
"We've basically asked the rescue teams to come to the mine site and they're ready and prepared to go underground as needed," he said.
Gov. Joe Manchin said the families of the four miners still missing from Monday's blast "realistically understand the sliver of hope" that the men could have survived the explosion and poisonous air.
Nevertheless, they "understood and were very agreeable" to the idea that fresh rescue efforts would have to wait to be sure rescue crews are not put in danger, Manchin said.
The explosion in the Upper Big Branch mine killed 25 miners.
Immediately after the disaster, rescue crews rushed into the mine, but were quickly forced to retreat because of the toxic conditions.
Manchin said that the only hope the men were still alive "is they made it to a chamber," referring to a specially constructed shelter in the mine that would provide them with clean air.
A refuge chamber sits 300 feet to the right of the first hole emergency workers drilled. It is four feet high and 20 feet long, room enough for 15 miners. There is 96 hours of oxygen in the chamber, but the supply would last longer if there were fewer men in the chamber.
Efforts to contact any survivors earlier today by banging a pipes failed to get a response.
For the first time today, images from inside the gates of the mine were seen from a location where teams were drilling some 1,100 feet down.
At one point, when the rescuers broke through a wall of the mine, air began to rush in -- a vacuum effect the workers weren't expecting. They had to place a fan on top of the drill hole to suck air out. That's when their tests finally revealed it was toxic.
When crews get the all clear, rescuers will enter the mine and ride what is called a "mantrap" for 30 minutes. From there, they will walk the rest of the way to the refuge chamber in search of survivors.
While the families of the missing men wait in agony, clinging to any shred of hope they can muster, the community remains stunned and angry about the loss of the rest.
Timmy Davis Jr. lost his father and two cousins in the explosion.
"He would tell us sometimes about how dangerous it was, but it didn't bother him," Davis said of his father, Timmy "Big Tim" Davis Sr.
"He just loved his job," he told "Good Morning America" today. "That's where he liked being at. If he made it out, he'd go back tomorrow."
Davis said his cousins, Cory Davis and Josh Napper, were "just good kids, trying to make a living."