Rescue workers have been pulled back yet again from their search for the four missing coal miners in West Virginia. Officials say signs of fire in the mine prompted the withdrawal.

On Thursday, search teams got frustratingly close to answers for the families of the missing miners.

They were just 500 feet from the emergency chambers where any survivors would be, but then they were ordered to retreat because of volatile gas.

J. Christopher Adkins, chief operating officer of Massey Energy Co., said that more drilling is needed to help clear the mine of the dangerous gas so that the rescue teams can go underground again.

He also said they found an alternate route that should save time if the crews are able to back into the mine.

"We think they are in danger and that's the whole intent of evacuating them from the mine," said Kevin Stricklin of the Mine Health and Safety Administration. "We couldn't let the rescue teams underground any longer based on the readings."

Stricklin said the families of the dead and missing understood the need to pull back the rescue attempt.

"It's a roller coaster for these people," Stricklin said. "It's very emotional. You can only imagine what it would be like."