[Vince Ferrer]

Here is some video from hikers on the volcano. I don't know if these are the ones who died, but things did not look good for them.

Mount Ontake Volcano Eruption In Japan Ontakesan 27/09/2014 | RAW VIDEO

It doesn't take lava or falling rocks to kill. Volcanic ash will destroy lungs, and volcanoes will release clouds of toxic gas that will suffocate. Don't stop and film it, just run.

[Darksheare]

Not to mention cooking you alive with the heat.

[SargeK]

Sulfur dioxide. They never had a chance.