Published: Apr 08, 2010 2:35 PM EDT

MONTCOAL, W.Va.  - Rescue crews began working their way through a West Virginia coal mine early Thursday in search of four miners missing since a blast killed 25 colleagues.

Gov. Joe Manchin say crews entered the Upper Big Branch mine about 30 miles south of Charleston at 4:55 a.m. EDT and hoped to reach the area where they might find the missing miners sometime before noon.

"They are advancing," Manchin told an early morning news briefing. "They'll move as rapidly as they possibly can."

Rescuers had to wait to enter the mine until four ventilation shafts were drilled to allow dangerous methane gas and carbon monoxide levels to drop to safe levels. Officials and townsfolk alike admitted they didn't expect to find any of the four missing miners alive more than two days after the massive explosion.

Poisonous gases have filled the underground tunnels since Monday afternoon's blast But officials are holding out hope that the miners had somehow survived the explosion by escaping into airtight chambers with enough food, water and air to survive for up to four days.

Authorities also want to recover 18 bodies of the known dead from the mine owned by Massey Energy Co.

Related: Gases force rescue crews to retreat from mine