It was a single shot, almost at point-blank, but kind of backwards and without proper aiming. It’s kind of how they tell you not to use a gun. It isn’t obvious from that video whether he had a clear shot; there were at least 2 other people around, who arguably could’ve been considered part of the threat, but also any number of workers at the food stands, and an unknown number of clients, who could’ve ended up being shot had he missed.
I’d say there was “some” neglect on his part… but how much, and how does it translate to the law, is hard to say without more data (and IANAL anyway).