An explosion on Saturday killed five workers in the Uricani mine in southwest Romania, in the latest fatal accident in the country's aging mines.
"There are no survivors, five people are dead," the mine's spokeswoman Oana Stoicuta told AFP.
"It's a tragedy down there," the mayor of Uricani, Danut Buhaescu, told Mediafax news agency.
Earlier, an official, Horia Radu, had said the four electricians and an engineer had been working on an electrical installation when the blast happened.
It occurred at a depth of around 400 metres (1,300 feet), mine officials said.
"At 14:30 (12:30 GMT) the workers said they had finished their job but some ten minutes later we smelt smoke coming out of the ventilation system," Stoicuta said.
A rescue team found the bodies five hours later.
The death toll could have been higher but for the fact that the maintenance work had been scheduled for the weekend, when mining operations were halted.
"There was a new explosion but the 15 rescue workers had all come back up to the surface and are safe and sound," Stoicuta added.
"The bodies of the five people killed have also been brought back to the surface," she added.
Local prosecutor Augustin Lazar said the local health and safety inspectorate had opened an investigation and their initial conclusions should be released within days.
The most likely theory was that the blast had been caused by a build up of methane, he added.
Constantin Jujan, director of the National Mining Company (CNH), said Saturday that the Uricani mine had acquired modern gas detection equipment in 2009 and 2010.
Interior Minister Train Igas arrived at the mine soon after the blast and met the relatives of the victims.
Igas said it was too early to know what had caused the explosion but added that an investigation was under way.
The Uricani coal mine is situated in the Jiu Valley, the most important mining area still operating in Romania. The mine employs some 800 people and is one of the oldest in the country.
Economy ministry official Florin Staicu said Saturday the mine would be closed down by 2018 as part of a mining sector restructuring plan overseen by the World Bank.
Since this programme Bank started in the late 1990s, the number of Jiu Valley miners has been slashed from 60,000 to 8,800 currently, according to trade unions.
Saturday's accident is the most serious since two blasts in the Petrila mine, also in the Jui Valley region, in November 2008, killed 13 people.
Three of that mine's former directors were jailed last November for breaches of the safety laws.
Trade unions regularly complain of poor working and safety conditions in Romanian coal mines and have called on the authorities to invest more in the sector to improve the situation.