MONTCOAL, W.Va. -- Rescuers have gotten no response from possible survivors to sound signals sent deep into a West Virginia coal mine where a blast killed 25 people and left four miners missing in the worst U.S. mining accident in over two decades.
Gov. Joe Manchin told an early morning news briefing Wednesday that rescue workers have banged on a drill pipe that reaches into the Upper Big Branch Mine.
"We did not get any response back," Manchin said. Officials said they also plan to set off a small explosion on the surface to send a seismic signal down to the mine.
Manchin also said that rescue workers have finished drilling a first vent hole in an attempt to remove toxic gas from the mine. They are trying to make a section of the mine safe enough for rescuers to search for the miners as hope for their survival grew dim.
Gov. Joe Manchin noted that the first completed hole entered the section about a football field's length away from the rescue chamber where officials hope the miners sought refuge from toxic gas.
Crews continue to drill three additional holes, all of which are meant to monitor the section's air and ventilate it with high pressure fans.
Two days after the blast that also left two hospitalized, the buildup of methane gas and carbon monoxide was too dangerous for anyone to enter and look for the last of the missing or to recover the bodies of 18 known dead.
Seven bodies were brought out after Monday afternoon's blast rocked the mine.
Once the mine is ventilated, teams would need four or five hours to reach the area where officials believe the miners are about 1,000 feet beneath the surface, said Chris Adkins, chief operating officer for Massey Energy Co., which owns the mine. The long section is about 20 feet wide with barely enough room to stand, a safety official said.
Searchers would have to navigate in the darkness around debris from structures shattered by the explosion and around sections of track that were "wrapped like a pretzel," said Kevin Stricklin, an administrator from the federal Mine Safety and Health Administration.
"There's so much dirt and dust and everything is so dark that it's very easy, as hard as it may seem to any of us outside in this room, to walk by a body," Stricklin said.
The missing miners might have been able to reach airtight chambers stocked with food, water and enough oxygen for four days. But rescue teams checked one of two chambers nearby and found it empty. Unsafe conditions prevented them from reaching the second.
Manchin said he continues to meet with the families, but had no updates regarding the two injured miners pulled to the surface after the explosion.
"The families are very resilient," said the governor, flanked by state and federal safety officials. "They know the odds are against us."
The death toll was the highest in a U.S. mine since 1984, when 27 people died in a fire at Emery Mining Corp.'s mine in Orangeville, Utah. If the four missing bring the total to 29, it would be the most to die in a U.S. coal mine since a 1970 explosion killed 38 at Finley Coal Co. in Hyden, Ky.
Associated Press writers Greg Bluestein, Allen G. Breed, Vicki Smith, Tom Breen and Tim Huber in West Virginia and Sam Hananel in Washington contributed to this report.