A gas explosion in a coal mine in northern Mexico on Tuesday killed three miners, injured one and left 11 others trapped deep underground.
Officials said chances were slim that anyone could have survived the massive blast.
Labour Secretary Javier Lozano said mine employees found the bodies of three miners at the front of the blast area, and given the size of the explosion and its force, "the outlook is very bad".
"The truth is that it does not allow us to hold out much hope," said Lozano, who was at the mine located in San Juan de Sabinas, Coahuila state, about 135 kilometres southwest of Eagle Pass, Texas.
He noted the blast was so strong that it severely wounded a 15-year-old boy who had been working on a conveyor belt outside the mine pit separating coal from tailings.
The boy was taken to a hospital in serious condition, said Jesus Espinoza, a spokesman for mining company BIMSA. Federal prosecutors later said both the boy's arms had been amputated and that he remained in serious condition.
Lozano said the boy's employment at the mine was an apparent violation of labour laws.
The announcement of the three deaths came just after Mexico said it was calling in mine rescue experts from Chile to help in the effort.
President Felipe Calderon called on Mexicans "to pray that they are still alive."
Lozano said five mine employees who had been lowered into the mine tunnel were able to operate safely, and that the gas appeared to have dissipated.
A wailing cry went up from about 80 relatives and friends of the trapped miners gathered at the site when a truck from the local morgue showed up at the mine.
"No, Lord, I don't want this to happen," said one woman, as relatives clutched one another and wept.
The mine had opened just over a month ago, and employed a total of about 25 miners.
The 14 miners had gone down the 60-metre deep shaft when the explosion happened early on Tuesday.
The national mine workers' union said in a statement that the mine's work force was not unionized, and it criticized what it called "the totally unsafe conditions in which coal mines in Mexico, and especially in this region known as the coal belt, operate."
Officials said they were investigating who was actually operating the mine, because there was conflicting registry data.
And the federal Attorney General's Office said it had opened an investigation in to the blast, which it said was caused by a gas buildup.
A similar blast caused by methane gas killed 65 miners in February 2006 at the Pasta de Conchos coal mine in San Juan de Sabinas, near where Tuesday's explosion occurred.
Rescuers eventually recovered the bodies of two miners from the 2006 blast but tons of wood, rock and metal, as well as toxic gas, prevented the recovery of the others.
Still smarting from criticism about the government's failings in mine safety, and their inability to recover the bodies from the 2006 blast, federal officials promised aid to the trapped miners' families and all necessary assistance in the rescue effort.