More than 30 people are feared to be dead after Mount Ontake erupted around midday Saturday and sent plumes of ash pouring down for about two miles. The search for victims was called off Monday due to fears about increasing levels of toxic gases. Military and other rescue workers had started airlifting bodies from the ash-covered peak of a Japanese volcano, but the toxic fumes forced them off the mountain. An official death toll has not yet been confirmed, but police say they believe 31 people found unconscious near the mountain’s peak are dead. They were discovered Sunday morning in a state of cardiopulmonary arrest after fresh eruptions of toxic gases thwarted earlier rescue efforts. Five new victims were also found on Monday. The Japanese mountain is popular with hikers who come to admire the fall foliage. As many as 250 hikers, including children, were stranded Saturday when it erupted without warning. It marks the first time the volcano has erupted in seven years. “It was like thunder,” a woman told Japanese public broadcaster NHK. “I heard boom, boom, then everything went dark.” Although Japan has experienced volcanic eruptions periodically, the last lethal one was in 1991, when 43 people were killed at Mount Unzen.