ISIS: Criminals/psychopaths in a lawless land

I do not have the stomach to watch the beheading videos. But tonight, the CBS Evening News aired the following clip (which does not show the beheading). However, at around 1:20, they show ISIS driving past cars and just randomly shooting up the occupants inside. For some reason, this vile act bothered me more than any of the other atrocities I've read about. These terrorists are essentially a bunch of thugs and psychopaths acting out in a land with no police force to arrest them and no elders to castigate them.