MONTCOAL, W.Va. — Officials are saying the rescue attempt of four missing West Virginia miners suffered a setback because crews met dangerous levels of gases underground.

Kevin Stricklin, an administrator from the federal Mine Safety and Health Administration, said today the rescue crews are in danger and they are evacuating the mine.

Rescue crews began working their way by rail car and on foot through the mine early today in search of four miners missing since a blast killed 25 colleagues in the worst U.S. mining disaster in more than two decades.

Gov. Joe Manchin said crews entered the Upper Big Branch mine, about 30 miles south of Charleston, just before 5 a.m. and hoped to reach the area where they might find the missing miners sometime before noon.

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

Rescuers had to wait to enter the mine until crews drilled holes deep into the earth to ventilate lethal carbon monoxide and highly explosive hydrogen as well as methane gas, which has been blamed for the explosion. The air quality was deemed safe enough for four teams of eight members each to go on what officials were still calling a rescue mission.

Once inside, they had to walk through an area officials have described as strewn with bodies, twisted railroad track, shattered concrete block walls and vast amounts of dust. Each team member was wearing 30 pounds of breathing equipment, lugging first-aid equipment and trying to see through total darkness with only a cap lamp to light the way.

By The Associated Press