Police Shooting an accident or murder?

A group of young men were on their way home from a new years party on the subway when they were pulled from the car by police. Police then handcuffed a few of the young men, and pulled a tazer on 22 year old Oscar Grant. From a video taken, Oscar is heard to be saying "Don't Tase me; I have a 4-year-old daughter. " After that, officers began to handcuff him on the ground and when he struggled one of officers pulled out his gun and shot him in the back. The bullet then ricocheted off the groud under him, and tore through his lungs. Oscar Grant died 7 hours later in the hospital.