A terrifying scene unfolded Sunday when Japan's Mount Ontake erupted -- while climbers were in the midst of scaling the 10-000-foot-high volcano.

About 30 of those climbers are feared dead. The volcano, which is a popular attraction for hikers in the autumn months, erupted without any warning.

A police spokesman said, "We have confirmed that more than 30 individuals in cardiac arrest have been found near the summit."