These guys had no exit strategy, they went into that mall with the intent of killing as many people as they could until they were killed.
it wasn't a jewelry heist where they wanted hostages or would not hurt you if you stayed out of their way.
I wonder what the typical response time of a swat team is to a mall on the outskirts of a city.
The actual shooting rampage lasted 3 hours from the first death to the last, but I suspect they killed most of the people within the first 20 minutes.
Four guys with AKs and no expectation of survival can do a lot of killing in the first 5 minutes.
I wouldn't like to be the shopper taking them on by myself with a pistol.