TheEusebius McKaiserShow

Authorities in the United States are still trying to determine why a 64-year-old man opened fire on a country music festival in Los Vegas on Monday.

It is the deadliest attack in US history.

Stephen Paddock opened fire, killing 59 people and injuring over 515 before killing himself.

READ: FBI search Vegas shooting suspect's home - Reporter

Ray White spoke to clinical psychologist Hayden Knibbs, chief psychologist in the police investigative psychology section.

The individual committing this type of a crime at a point starts to feel very frustrated or very angry because of some sort of challenge that is happening in their life, they normally feel quite wronged.

— Hayden Knibbs, clinical psychologist

At this stage, they are classically unable to deal with these emotions and because of it, they build up more frustration - and then fighting back becomes a viable option.

— Hayden Knibbs, clinical psychologist

In fact there is a lot of similarities that we see in the process akin to suicide...a lot of the time these types of perpetrators are very isolated.

— Hayden Knibbs, clinical psychologist

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