Well, just a wild ass guess but it was an 'armed robbery'. I gotta assume they had guns. So, in this situation what's the best way to prevent their use...cuff em all while you sort it out IMO.
Damn, I was right: When they searched the car, they found two loaded firearms. Now the question is...if able would the perp have used them, perhaps killing some innocent folk/s in an effort to avoid arrest? We'll never know and IMO that's a good thing.