Police said Michael Brandon Hill eventually surrendered "without incident, without resistance," WSB-TV in Atlanta reported. But he had opened fire when police responded to the Ronald McNair Discovery Learning Academy, although no one was injured.
"When we received the call and we engaged, he started to fire from inside the school at our officers. He had one or two of the staff members inside the main office. He was holding them captive," DeKalb County police Chief Cedric Alexander said.
Hill was dressed in black and was armed with an AK-47 and several other guns, Alexander said.
One woman who was held in the office said Hill asked her to call police and WSB. She remained on the line with the TV station until after Hill's surrender.
Alexander said firefighters cut a hole in a house next to the school to allow children to get away without leaving the school by the front entrance. Firefighters and police feared the gunman might have explosives in his car or on school property.
A nearby Walmart became a staging area where children were reunited with parents.