A cave-in Wednesday at a coal mine near the northern Mexico town of Barroteran left at least five workers trapped underground, authorities in Coahuila state told Efe.
Authorities have not been able to confirm that the trapped men are alive, state emergency services spokesman Francisco Martinez Avalos told Efe.
"The rescue teams are already there," he said. "Municipal and state emergency services, municipal police, firefighters, contributing in these efforts."
The cave-in may have been caused by "a softening of the soil, an explosion, a flood," Martinez said.
While Milenio Television reported the miners could be trapped 50 meters (164 feet) underground, the state government spokesman said the exact location of the men remains uncertain.
The network also said the accident happened as the workers were digging a ventilation shaft.
Coahuila is home to numerous coal mines, many of which fall short of official safety standards.
A February 2006 gas explosion at the Pasta de Conchos coal mine in San Juan de Sabinas, Coahuila, killed 65 men. Only two of the bodies were ever recovered. EFE