Considering this tidbit in the usatoday article posted above, the police were likely on high alert when confronting him...
--Zambrano-Montes was arrested early last year for assault after throwing objects at officers and trying to grab an officer's pistol, court records show. Police this week say Zambrano-Montes refused to comply with orders to drop what he was holding and withstood a shock from a stun gun.--
I don't really believe we can sit here behind our laptops in our comfy chairs and know what it's like to be in these situations. Yet another reason why I never wanted to be law enforcement. I'm fairly certain some police want to dispatch their own versions of justice, possibly motivated by racial aggression and hatred of their views of society.
I've never had a single problem with a police officer when pulled over for traffic violations, stopped on the street for taking a drunk piss, etc. I've also never became belligerent, ran away, attempted assault, etc. But I also weigh in that I'm Caucasian and most likely to be dealt with differently than someone of another race in the same position as me. So I understand the psychology behind other races reacting the way they do towards police officers.