DECATUR, Ga. (WXIA) -- Police said the "potential was there to have another Sandy Hook" at McNair Learning Academy.
The public defender for Michael Brandon Hill, the man accused of firing shots at McNair Discovery Learning Academy in DeKalb County on Tuesday, waived his first appearance in DeKalb Magistrate Court.
During a police press conference Wednesday, investigators said Hill got the gun from an acquaintance's home, and had nearly 500 rounds of ammo.
Officers from the Bureau of Alcohol, Tobacco and Firearms have the weapon and are trying to learn more about how Hill got it.
Police say Hill fired shots in the school before stepping outside and firing at police. Police did return fire.
Police are talking to Hill's friends and family to learn more about the suspect. They are also still trying to determine a motive.
Police did show a picture that Hill took on his cell phone holding the gun he used.
Twenty-year-old Hill, was arrested earlier this year for threatening to kill his brother.
A police report from Henry County Police shows that Hill was taken into custody on March 13 and charged with terroristic threats.
Hill's brother, Timothy Hill, who lives in McDonough, told police in late December 2012 that the suspect sent him a Facebook message saying "that he would shoot him in the head and not think twice about it," according to the police report.
Timothy Hill told police that Michael Hill suffers from mental issues. Timothy Hill also said he was in fear for his life, and that he did not know his brother's address.
Michael Hill was tracked down and then arrested by Henry County Police more than two months after making the Facebook threat.
He faces charges of terroristic threats, firearm possession and aggravated assault on a police officer in Tuesday's shooting.
Hill's public defender waived his first appearance at DeKalb County Magistrate Court Wednesday afternoon. In a statement, Claudia Saari with the Office of the Public Defender said Hill is being represented by members of the office's Mental Health Division.