LONDON (AP) - British rescue workers pumped water Thursday from a flooded coal mine in south Wales in an attempt to reach four trapped miners.
Rescuers said they had not been able to contact the men, trapped 300 feet (90 meters) underground at the Gleision Colliery near Swansea, and it wasn't immediately clear what condition they were in or what caused the mine to flood.
Fire department official Chris Margetts said he was "very hopeful and optimistic" the four miners could be rescued, through other officials acknowledged that rescuers had no communication with them.
"The good news is water levels are receding slowly," Mines Rescue Service official Mark Tibbott told Sky News television. He said four pumps were taking water out of the mine and he hoped the "men are in an air pocket."
The mine shaft was not blocked by fallen rock, but water was preventing emergency workers from reaching the men, South Wales Police Supt. Phil Davies said.
The trapped miners were identified as Phillip Hill, 45, Charles Bresnan, 62, David Powell, 50, and Garry Jenkins, 39.
Prime Minister David Cameron said the emergency services would be provided with any assistance they needed to carry out a rescue.
"My thoughts are with those missing and their family and friends at this very difficult time," Cameron said in a statement. "Every support will be given to the emergency services to ensure they continue to do all they can. In due course, we must ensure we fully understand and learn from the causes of this accident."
Police said three other miners managed to get out of the mine after the accident Thursday morning. The head of the Wales's regional government, First Minister Carwyn Jones, said one miner was taken to a hospital in critical condition.
The small mine, burrowed into a steep and isolated hillside, is one of the few remainders of Britain's once-mighty coal mining industry, which for decades dominated the economy of South Wales.
In the 1980s, Britain's Conservative government under Margaret Thatcher closed down most mines after an epic yearlong battle with the left-led miners' union. In 1984, the year of the strike, there were 196,000 miners working in Britain; by 2007, there were about 6,000.
The worst mining accident in British history was in 1913, when 439 miners were killed in a gas explosion at the Senghenydd colliery in South Wales. In a 1966 disaster that shocked the world, an avalanche of coal sludge buried a school in the village of Aberfan, killing 116 children and 28 adults.
Seven people have been killed in mining accidents in Britain since 2006, according to Health and Safety Executive statistics.