Two dogs were running loose and one of them had a bad attitude. The dog began biting at a child (who sounds like received wounds but hopefully none of them significant).
An officer patrolling in the area heard the screams of the children and ran to the scene. He positioned himself between the dog and victims, getting them to safety. The dog became agitated and aggressive towards the officer who kindly refrained from immediately shooting the dog, instead fighting him off with his baton while calling animal control. This guy is pretty amazing, because he can multi-task under stress.
It was only after the dog really became super agro and tried to eat the officer did he open fire, eventually killing the dog.