Rescue workers have suspended their search for 65 men trapped in a coal mine for almost six days in northern Mexico because of safety concerns.
Officials believe many of those trapped may have already died
Mine officials said machines are to be used to lower dangerous gas levels to enable the search to resume.
The men have been stuck deep in the mine in the northern state of Coahuila since an explosion.
It is thought some miners may have survived if ventilators in the shaft worked and air pockets developed.
Arturo Bermea, a senior executive at mine owner Grupo Mexico, told weeping relatives and friends of the trapped men outside the mine the suspension would last for two or three days.
He said it was for the safety of the rescue teams because there was a risk of explosions due to the presence of methane gas in the mine's tunnels.
Families, who have been camping out in the cold for several days, reacted angrily and some had to be held back as they tried to force their way to the entrance.
Mr Bermea said holes would be drilled into the mine from the surface to suck out the gas, which is lethal at high levels of concentration.
"We have always believed there is hope that the workers are alive and we will continue working indefinitely," Mr Bermea said.
Rescuers fear many of the miners may already be dead due to a lack of oxygen in their sections of the mine when the blast occurred.
Sunday's explosion is thought to have been caused by gases igniting.
Most of the workers are thought to be trapped in tunnels at least 2km (1.25 miles) into the mine, which lies near the town of San Juan de Sabinas, 100km (60 miles) from the Texas border.
Ten men who were underground escaped safely, and another 12 were rescued, suffering from burns and broken bones.