An accident at a coal mine in northern Mexico left seven workers trapped on Friday, authorities said.
According to initial investigations, a flood caused the collapse at the small-scale mine in the Muzquiz township, the state of Coahuila's labor department said.
"Some people who were working were trapped inside the mine," it said in a statement.
National Guard deployed for the rescue
The National Guard said on Twitter its personnel "were deployed in the area to provide security and allow the rescue of trapped workers."
Mexico's President Andres Manuel Lopez Obrador said he had assigned personnel from the security, labor and civil protection ministries to the area to help the National Guard and the military.
"We are watching and in coordination with municipal and state authorities," he said on Twitter. "We hope that the rescue is favorable for the families and for everyone."
The mine appears to be a deep, narrow, open coal pit with steep earth walls.
The federal civil defense office said water was being pumped out of the pit to allow rescue work to continue.
Coahuila's tragic mine accidents
Coahuila is Mexico's main coal-producing region. It has been hit by a series of fatal mining accidents in the past.
A methane gas explosion at a coal mine claimed 65 lives in February 2006.
Two bodies of the 65 were recovered but the rest are still at the site as wood, rock, metal and toxic gas hindered their recovery.
Families of the 63 miners have long appealed to Mexican authorities to recover their bodies.
fb/rc (AFP, AP)