What happens is a pyroclasitic flow coming down from the volcano. It is a mix of ash and stones at extremely high temperature at very high velocity. Think of it as a river of heat combined with ash and stone and incinerating temperatures. Those in the direct flow were lucky. Their death was painful but quick. Those on edge may or not survive. Either way it will be brutal.
I am pretty sure that last photo showed the people inside the volcano and not on the sides.
What was the last thing that went through their heads ?