An explosion ripped through a coal mine in West Virginia on Monday, killing 12 workers and leaving 10 unaccounted for in one of the worst US mining disasters in recent years, officials said.
The blast occurred towards the end of the afternoon at the Upper Big Branch mine run by Performance Coal Company, a subsidiary of Massey Energy, in the town of Mountcoal located some 30 miles (50 kilometers) south of Charleston.
"Our prayers go out to the families of the miners. We want to assure the families of all the miners we are taking every action possible to locate and rescue those still missing," the company's chairman and chief executive, Don Blankenship, said in a statement.
Kevin Stricklin, administrator of coal at the Mine Safety and Health Administration, told a midnight news conference in West Virginia that 12 miners were killed in the disaster, and 10 remained unaccounted for, the Charleston Gazette reported.
President Barack Obama telephoned West Virginia governor Joe Manchin to offer, "his deepest condolences to the those who lost loved ones earlier on Tuesday in the tragic incident."
Obama told Manchin "that the federal government stands ready to offer whatever assistance is needed in this rescue effort," a White House statement said.
A massive rescue operation was launched after the blast as local and volunteer firefighters rushed to the scene along with a fleet of ambulances and mine safety workers tried to contact missing miners underground.
"They have gotten 10 out so far, eight were dead on arrival and two were transported to hospital," the emergency official told AFP, confirming that one was flown by helicopter and the second went by road.
A spokesman for the Raleigh County emergency services later said seven were being reported as confirmed killed.
Details about the rescue operation were sketchy, in part because mobile phone services are intermittent at best in the mountainous area of the mostly rural state.
Manchin, who rushed home from a vacation upon learning the news, said Obama had promised "every asset available" to help in the rescue effort.