That's nuts. It looks like the white minivan was driven by someone eluding arrest, then after he totals it and is ejected from it, the cops finally "catch" him and take the opportunity to beat the shit out of him. As opposed to first checking his condition and possibly providing medical attention?
The only thing I can think of is that this particular suspect already shot some fellow officers or maybe some civilians, and the cops weren't gonna show any mercy. Pretty despicable, actually, but in a way I can kinda understand it. After a high-speed chase, adrenaline is pumping, the cops are all wired up, and if they already had reason to hate this guy and/or otherwise be less than professional in their treatment of him, it's hard to turn that off. I just figure the guy had it coming.