Newly released surveillance video shows Hill walking into the school after being let in the front door by a woman with a child.

Police said Hill confronted office staff around 1 p.m. and told bookkeeper Antoinette Tuff to call the local media. She told a WSB-TV that the gunman wanted the news to "start filming as police die."

Police said Hill opened fire at the school and was armed with hundreds of rounds of ammunition, but he was eventually apprehended peacefully.

No students, faculty or law enforcement officers were injured in the ordeal.

Hill was sentenced to 40 years in prison, with 20 to serve.