Gunman Brought 500 Rounds to Atlanta-Area School

The man who walked into a DeKalb County, Ga., elementary school Tuesday armed with an AK-47 brought nearly 500 rounds of ammo, authorities said Wednesday.

Michael Brandon Hill , 20, entered McNair Discovery Learning Academy and headed to the office, where he began loading the weapon. Hill reportedly threatened to shoot officers. Hill briefly exchanged gunfire with DeKalb County PD officers before surrendering to police, reports WSB-TV .

Hill obtained the weapon from an acquaintance but it wasn't immediately clear whether he stole the rifle, according to the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF).

Hill is mentally ill and was reportedly not taking his medication, reports the Associated Press .