I'd step out of the path, personally. If you just saw a truck run down pedestrians in a crosswalk after running a red light, driving around other cars to get at the pedestrians, would you (a) Do nothing. (b) Report it by phone to police while trying to render aid. (c) try to get in front of a moving truck with your body to prevent his escape (having just seen him run over pedestrians crossing in a crosswalk with the light) or (d) pull your weapon to shoot the tires of the truck in order to disable the fleeing felon's escape.?? I have heard, nothing stops a bad guy with a truck, like a good guy with another truck or maybe a full magazine and a willingness to get involved.
Like I said, we'll have to wait and see on the law enforcement reports.