The death toll for the Mount Ontake volcano eruption in Japan has climbed to at least 36, reports Reuters. Japan's second most active volcano erupted without warning Saturday, leaving hundreds of hikers stranded as the mountain spewed ash and rubble. More than 500 rescue workers were sifting through the eight-inch-thick layer of ash, but poisonous gas halted their efforts Monday.

The Mount Ontake volcano eruption is the first fatal one since 1991, when the Mount Unzen eruption killed 43 people. Mount Ontake's last major eruption occurred in 1979.

Japanese soldiers recovered eight bodies near the summit of Mount Ontake Monday. Soldiers recovered four bodies on Sunday, and there are 24 bodies near the summit that have yet to be recovered, reports the Associated Press, as the volcano is actively erupting and sending gas and ash into the air. Earlier reports indicate 150 people were forced into shelters located on Mount Ontake while another 230 hikers were able to escape from the mountain. 

Mount Ontake, with a 3,067 meter (10,062 feet) peak, is a popular hiking destination for families. The eruption occurred without warning and Japan's Meteorological Agency said it would evaluate its monitoring systems going forward. There were reports of tremors in the region but no physical changes to Mount Ontake that would have indicated an imminent eruption.

Earlier in September, the Philippines evacuated 12,000 people around Mount Mayon after the Philippine Institute of Volcanology and Seismology detected earthquake activity around the volcano and rockslides. Iceland's Bardarbunga volcano had similar seismic activity, which prompted travel warnings.