By Ma. Elena Espejo (staff@latinospost.com) | First Posted: Sep 29, 2014 01:58 AM EDT

At least 31 people were presumed dead after Japan's Mount Ontake erupted without warning on September 27, Saturday, effectively trapping hundreds of hikers as the volcano spewed out clouds of rock and ash and toxic fumes.

Police confirmed four deaths, all male, out of the 31 found unconscious near the peak of the volcano, while the other victims were found in "cardio-pulmonary arrest." Aside from those who have suffered cardiac arrests, others have been injured, some with broken bones. Helicopters brought down a number of severely injured people off the mountain.

According to Reuters, hundreds of people, children included, were stranded in the mountain. Others have made their way down but about 40 people spent the night wrapped in blankets in the basement of mountain lodges near the volcanic peak.

In a report by CNN, the Fire and Disaster Management Agency said that authorities are having difficulties identifying the exact number of people trapped in the mountain. They are also still trying to confirm the whereabouts of the missing ones.

Video footage on the Internet showed people being engulfed by darkness and smoke as they descend from the peak.

"All of a sudden ash piled up so quickly that we couldn't even open the door," Shuichi Mukai says, a worker in a mountain hut just below the peak, reports ABC.

The mountain lodge quickly filled with hikers seeking refuge.

"We were really packed in, maybe 150 people. There were some children crying, but most people were calm. We waited there in hard hats until they told us it was safe to come down."

The same report from CNN noted that the Japan Meteorological Agency has raised Mount Ontake's Volcanic Alert Level from 1 to 3, which means the public is prohibited from approaching the volcano. The agency also warned that another large eruption could take place in the next few days. Mount Ontake continued to erupt all throughout Sunday. Officials said that 17-20 inches of volcanic ash covered the ground in some areas.

The volcano's eruption caused delays at several airports as planes changed routes to avoid the plumes of smoke and ash.

Mount Ontake, a popular hiking spot located about 200 kilometers west of Tokyo, is the second tallest volcano in Japan. Its last major eruption was in 1979, which lasted for months. Smaller volcanic activities were also reported in 1984, 1991, and 2007.

Japan is no stranger to volcanic eruptions, as it lies on the Pacific Ring of Fire, an area where earthquakes and volcanic activities are formed.