MOSCOW >> Russian authorities late today called off a search for dozens of people still missing about 250 meters (820 feet) underground, following a coal mine fire in Siberia that killed at least 14 miners and rescuers.

Rescue teams were rushed out of the mine for safety reasons because of a buildup of explosive methane gas and a high concentration of toxic fumes from the fire. It was feared that the 38 missing people were already dead as their oxygen supply would have finished within hours even if they survived the blaze.

Authorities said 11 miners were found dead and three rescuers also died later while searching for others trapped in a remote section of the mine. Regional officials declared three days of mourning.

Kemerovo Governor Sergei Tsivilyov said 35 miners remained missing, and their exact location was unknown. Emergency officials reported three rescuers also missing.

A total of 285 people were in the Listvyazhnaya mine in the Kemerovo region of southwestern Siberia when a fire erupted and smoke quickly filled the mine through the ventilation system. Rescuers led to the surface 239 miners, 49 of whom were injured.

Russia’s Deputy Prosecutor General Dmitry Demeshin told reporters that the fire most likely resulted from a methane explosion caused by a spark.

Explosions of methane released from coal beds during mining are rare but they cause the most fatalities in the coal mining industry.

The Interfax news agency reported that miners have oxygen supplies normally lasting for six hours that could be stretched for a few more hours but would have expired by late Thursday.

Russia’s Investigative Committee has launched a criminal probe into the fire over violations of safety regulations that led to deaths. It said the mine director and two senior managers were detained.

President Vladimir Putin extended his condolences to the families of the dead and ordered the government to offer all necessary assistance to those injured.

In 2016, 36 miners were killed in a series of methane explosions in a coal mine in Russia’s far north. In the wake of the incident, authorities analyzed the safety of the country’s 58 coal mines and declared 20 of them, or 34%, potentially unsafe.

The Listvyazhnaya mine wasn’t among them at the time, according to media reports.

Russia’s state technology and ecology watchdog, Rostekhnadzor, inspected the mine in April and registered 139 violations, including breaching fire safety regulations.