Why did the police taze Dalian Atkinson?

A neighbor called the police to Dalian's father's home due to a domestic dispute. The neighbors reported that he kicked in the door to his father's home, and there was screaming and crashing. According to the neighbors, when the police arrived, they told him to quit advancing, but he kept coming towards him, and so they tazed him. His father stated, "I don't know if he was drunk or on drugs but he was very agitated and his mind was upset."