Local people have held vigils for those who died in the mine blast
US rescue teams have pulled out of a West Virginia coal mine where they were searching for four missing workers trapped after an explosion on Monday.
At least 25 miners were killed in the blast, the worst mining disaster in the country since 1984.
The state governor said the crews, who had entered the mine on rail car and foot, had been forced out after finding dangerous levels of gas inside.
Officials said that they had not ruled out re-entering the mine later on.
"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.
'Sliver of hope'
Rescuers were reported to have reached some 150m (500ft) from an airtight chamber where they hoped the trapped miners might have sought refuge.
Governor Joe Manchin described this possibility as the only "sliver of hope" of finding the missing four alive.
Rescuers had already been forced to wait until holes had been drilled into the Upper Big Branch mine, south of Charleston, to ventilate it after lethal gases built up along its damaged tunnels.
The bodies of 18 of the 25 confirmed dead workers remain inside the damaged mine.
Conditions in the mine caused by the explosion have made the rescue operation extremely difficult, with dirt, dust and darkness also impeding rescuers' efforts.
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