There's a pattern in many of these incidents, including this one, the recent Paris airport incident, the Nice truck attack etc.  They are all men with petty criminal pasts and little religious belief. The Nice driver was a petty criminal, into drugs, drinking, womanizing etc.  1/3 of the people he killed were themselves Muslims.  

The recent Paris attacker had drugs in his apartment and hung out in bars. He had a pistol with buckshot. Why did he suddenly shoot the police officer on a routine stop?  Why did he tell his father he'd made a mistake? 

The investigations seem to quickly conclude "radicalization" without formal evidence. i.e. if they can't figure it out quickly then the person must have been "self-radicalized via the web".  Why the rush to judgement?  There's something VERY serious going on here, and it needs real thought and action. 

What made these (not very religious) men commit these crimes? Were they on drugs? Were they coerced or blackmailed?  More info is needed.