By Michael Holden
LONDON (Reuters) - Emergency services were carrying out a major rescue operation on Thursday after four miners became trapped following a flash flood in a coal mine in south Wales.
Specialist teams from across Britain including cave divers and a mines rescue team have been brought in to try to locate the men, trapped 90 meters below the surface in the small Gleision Colliery in the Swansea Valley.
Three other miners managed to escape, although one is now in hospital and said by media to be in a critical condition.
"They just said they could hear the water come in, they turned round and they ran," said Chris Margetts from the Mid and West Wales Fire Service.
The miners who escaped said a wall to an old working had failed, which had flooded the main 250 meter route into the mine. Rescuers said they were hopeful that the trapped men would head into old shafts and tunnels where there would be pockets of air.
"They're experienced miners. They know the layout of the mine. They would know where to go in this situation," Margetts told reporters.
"We're very hopeful, we're very optimistic. We will work until we have a successful conclusion."
The emergency services were working to pump out the water before launching a search of the other shafts and tunnels. Margetts said conditions were favorable, and air supply was good, but they had not been able to contact the trapped men.
Police said Gleision was a small, private mine. According to a history on the Miner's Advice website, the mine operates under a very steep hillside above the banks of the river Tawe.
"It is a safety lamp mine with severe water problems which require the use of a powerful sump pump," the website says.
(Reporting by Michael Holden; editing by Keith Weir)