Two men remain trapped 140 meters (459 feet) underground after a cave-in at a coal mine in central Chile, authorities said Tuesday.

The secretary of mining in the Biobio region, Luis Ulloa, said that while the accident took place at 3:50 a.m., the owners of the Buen Retiro mine did not report the emergency until after 11:00 a.m., a delay he described as "very grave."

"I regret the time that passed between the occurrence of the cave-in some 140 meters underground and the moment of the notice, which caused the loss of valuable time," he told Radio Bio Bio.

The mine owners may be subject to "the most serious sanctions," depending on the outcome of the official accident investigation.

The trapped miners, identified as Richard Perez Jara, 21, and Reinaldo Brevis, 39, are fine and in contact with people outside the mine, authorities said. EFE