A lot of these incidents overnight don't make a lot of sense. These guys are obviously very smart and well trained and have put a lot of thought into the original attack, yet now they are going haphazardly. The robbing of the 7-11, made absolutely no sense! They should have had sufficient money before the original attack so they didn't need it now. The killing of the police officer certainly was not in their best interest, either. Thankfully they didn't kill the owner of the car they hijacked, but that was certainly another error that made it easier for authorities to follow them.
The fact they were still in the Boston area instead of far away from the city also seems like another bad move on their behalf. Thankfully, maybe their stupidity will lead to their capture or death before they hurt anybody else.