Three miners are still missing after an accident Friday at a Coahuila coal mine, where 150 people are involved in the search.

The bodies of four miners have been recovered since the accident, which followed heavy rainfall at the Micarán mine in Múzquiz. All four drowned in the flooded mine.

Landslides blocking access to part of the mine have so far jeopardized efforts to reach the final three.

Most of the water has been extracted from the mine, but the rescue workers have been impeded by mud and rocks blocking their path.

Some of those involved in the operation said they are still a long distance from the part of the mine where the missing miners are believed to be located. The small-scale mine is about 800 meters long and 100 meters deep; a deep and narrow open coal pit with steep sides, according to the Associated Press.

Governor Miguel Ángel Riquelme confirmed the unlikelihood of finding survivors on Sunday. “Oxygen is an issue due to the time that has already passed,” he said.

Coahuila Attorney General Gerardo Márquez said the miners are probably in the most flooded part where one of the walls is also damaged.

He added that an investigation into the accident would be conducted by the federal Attorney General.

Rescue experts, technicians from the mining company, public safety officers and National Guard sniffer dogs are all involved in the rescue effort.

With reports from El Universal