(ABC News) -- As a gunman terrorized an Atlanta-area elementary school today, a school clerk said she was the one who convinced him to empty his pockets and backpack of ammunition and to get down on the floor so police could apprehend him.
In an exclusive interview on "World News with Diane Sawyer," Antoinette Tuff described how she watched the suspect -- Michael Brandon Hill, 20, from the Atlanta area, officials and sources said -- load up with ammunition in front of her and several other employees who were being held hostage.
"[I saw] a young man ready to kill anybody that he could and take any lives he wanted to," Tuff said.
The lone suspect entered Ronald E. McNair Discovery Learning Academy in Decatur, Ga., this afternoon carrying an AK-47 assault rifle and other weapons, said Chief Cedric Alexander of the Dekalb Police.
Police identified the suspect as Michael Brandon Hill, 20, and said he will face charges including aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon.
"Detectives continue to interview the suspect at police headquarters," a police statement noted.
Sources told ABC News Hill recently was arrested for alleged terroristic threats and acts.
A man with the same name and age was arrested five months ago in McDonough, Ga., according to online records and court records. He entered a negotiated plea on July 16 and was sentenced to three years' probation and anger management.
During today's standoff, Tuff said the suspected gunman "went outside several times and shot at police officers."
He also ordered staffers to call a local television channel, ABC affiliate WSB-TV, to request that a camera crew record him "killing police," WSB reported.
"He told me he was sorry for what he was doing. He was willing to die," Tuff said.
The school clerk said she tried to keep the assailant calm by asking him his name but, she said, at first he wouldn't tell it to her.
Then, he began listening to her tell her life story. She said she told him about how her marriage fell apart after 33 years and the "roller coaster" of opening her own business.
"I told him, 'OK, we all have situations in our lives. I went through a tragedy myself,'" she said. "It was going to be OK. If I could recover, he could too."
Then Tuff made the request that she said helped end the standoff. She said she asked the suspect to put his weapons down, empty his pockets and backpack and lay on the floor.
"I told the police he was giving himself up. I just talked him through it," she said.
Police, including U.S. marshals, entered the school and found the gunman in the office. He exchanged fire with the officers but ultimately surrendered, Alexander told reporters.
No students were harmed and the suspect was taken into custody.
"Once we had him in custody, we secured the entire school," Alexander said.
SWAT teams were sent classroom to classroom to evacuate students, some as young as pre-kindergarten.
Authorities have yet to establish a motive or determine whether the shooter had a link to the school.
Police planned to evacuate the children through the front of the school, but the risk of a bomb in the suspect's car led them to find an alternative route. Instead, police cut a large hole in a stretch of fence behind the school and led children down an embankment. There they were placed on school buses, accounted for, and later reunited with their families at a nearby Walmart.
"It's a blessed day: All of our children are safe," said Michael L. Thurmond, interim superintendent of the Dekalb County School District.
Police continued to investigate the car the gunman drove to the school after bomb-sniffing dogs detected explosives. Police later blew up the car's trunk and towed away the car, but found no explosives, a police official said.
Authorities believe the man may have entered the school by closely following a person authorized to enter the building, however once inside, he only went as far as the front office.
The shooting came on just the second week of classes at the charter school.
School safety and gun control were again thrust into the national spotlight last year when Adam Lanza, 20, killed 20 students and six adult staff members at Sandy Hook Elementary School in Newtown, Conn.
ABC News' Diane Sawyer, Mike Levine, Steve Osunsami and Michael S. James contributed to this report.
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