Though the school has a system where people must be buzzed in by staff, the gunman may have slipped inside behind someone authorized to be there, Alexander said. The suspect, who had no clear ties to the school, never got past the front office, where he held one or two employees captive for a time, the chief said. Hill is charged with aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon.
A woman in the office called WSB-TV as it was happening to say the gunman asked her to contact the Atlanta station and police. WSB said during the call, shots were heard in the background. Assignment editor Lacey Lecroy said she spoke with the woman who said she was alone with the man and his gun was visible.
"It didn't take long to know that this woman was serious," Lecroy said. "Shots were one of the last things I heard. I was so worried for her."
DeKalb County Schools Superintendent Michael Thurmond praised faculty and authorities who got the young students to safety, staying calm and following plans in place. All teachers and students made it out of the school unharmed.
"It's a blessed day, all of our children are safe," Thurmond said at the news conference. "This was a highly professional response on the ground by DeKalb County employees assisted by law enforcement."
School volunteer Debra Hayes said she encountered the suspect without knowing it.
She stopped by the office at the end of her shift and saw a man talking to a secretary but she did not see a gun.
"I heard him say, 'I'm not here to harm any staff or any parents or students. He said he wanted to speak to a police officer."
"By the time I got to 2nd Avenue, I heard gunshots," she said.
Complicating the rescue, bomb-sniffing dogs alerted officers to something in the suspect's trunk and investigators believe the man may have been carrying explosives, Alexander said. Officials cut a hole in a fence to make sure students running from the building could get even farther away to a nearby street, he said. SWAT teams then went from classroom to classroom to make sure people were out.
Police had strung yellow tape up blocking intersections near the school while children waited to be taken to Wal-Mart where hundreds of people were anticipating their arrival. The crowd waved from behind yellow police tape as buses packed with children started pulling up along the road at the store. The smiling children waved back.
Regional superintendent Rachel Zeigler used a megaphone to say children were organized on the buses by grade level and that each bus would also be carrying an administrator, a teacher and a Georgia Bureau of Investigation officer. Relatives had to show ID, sign each child out and have their photo taken.
The school has about 870 children enrolled. The academy is named after McNair, an astronaut who died when the space shuttle Challenger exploded on Jan. 28, 1986, according to the school's website.
Jonessia White, the mother of a kindergartner, said the school's doors are normally locked.
"I took (my son) to school this morning and had to be buzzed in," she said. "So I'm wondering how the guy got in the door."
Jackie Zamora, 61, of Decatur, was at the Wal-Mart waiting and said her 6-year-old grandson was inside the school when the shooting was reported and she panicked for more than an hour because she hadn't heard whether or not anyone had been injured.
Since shootings in classrooms all over the country, the massacre at Connecticut's Newtown Elementary being the freshest in people's minds, schools have implemented security from metal detectors to armed guards. McNair had its own safety precautions.
White said the school has a set of double doors where visitors must be buzzed in and show identification to a camera to be allowed in.
"I don't know how this could happen at this school," Zamora said. "There's so much security."