MEXICO CITY — Two more bodies were found Wednesday at a small coal mine in a northern Mexico border state after the shaft flooded and partially collapsed, bringing to six the number of confirmed dead.

Hopes for finding the lone remaining missing miner alive have dimmed, but authorities said that search efforts would continue.

The national civil defense office said body of the fifth miner had been pulled out of the mine, while efforts to extract the sixth continued. The bodies were in such poor condition they could not be immediately identified.

The accident occurred late last week at a small coal mine in Coahuila state, where there have been complaints for years about unsafe conditions at coal mines.

President Andrés Manuel López Obrador said a dam or holding pond had collapsed, causing the flood.

The Micarán mine, located in Muzquiz township, appears to be a type of deep, narrow, open pit with steep earthen walls, with at least one tunnel at the bottom burrowing into the coal face. The area is about 80 miles (130 kilometers) southwest of Eagle Pass, Texas.

Coal mines in the area have been hit by deadly accidents in the past. An accident on Feb. 19, 2006, in the Pasta de Conchos mine in nearby Sabinas, Coahuila, killed 65 miners, but only two bodies were recovered.

Mexican authorities called off that search and closed the mine five days after the accident, arguing that it was unsafe due to toxic gas.

Many of Coahuila’s small-scale mines have rough logs and tin roofing used to shore up tunnels. Miners descend atop crude coal buckets on cables pulled by car engines.

The issue is a key one for López Obrador, who has promised to get justice for miners’ families, while simultaneously increasing the amount of coal the government purchases to burn in power plants.