The 12 local civil protection mountaineers had embarked on their mission after climbers reported seeing a frozen skull 310 meters (1,000 feet) from the peak of the 5,610-meter Pico de Orizaba on Monday.

The second body was found 150 meters away, and it was also frozen and mummified, said Juan Navarro, mayor of the town of Chalchicomula de Sesma, near the mountain in central Puebla state.

“It was impossible to conduct the rescue this time. Fog prevented the work,” Navarro told AFP, adding that only two of the climbers were able to reach the location of the bodies.

After the first body was spotted, Mexican authorities received phone calls from people in Spain and Germany who believe it could be a relative, he said.

But local officials suspect that the cadavers correspond to two of three Mexicans who went missing after an avalanche 55 years ago.

Pieces of clothing found on both bodies could help identify them, Navarro said.

The recovery effort will resume Friday with the help of a helicopter.

The bodies will be taken to the Puebla state prosecutor’s office to undergo DNA identification tests.

The mountain, also known as the Citlaltepetl volcano, is popular among climbers, though some have got lost or suffered fatal accidents in the past.