I heard there were quite a few people in the park, and the kid had been waving the gun around.
But the video of the shooting clearly shows that in the several minutes prior to the arrival of the police that there were no people around the kid and he wasn't waving anything. The cop car pulls up and within 2 seconds after it stops the kid is lying on the ground, shot. So where was the threat to the police or anyone else that justified the shooting?