ATLANTA (CNN) -- He slipped in to the suburban Atlanta elementary school, police say, behind someone else -- armed with an AK-47 type weapon and about 500 rounds with ammunition.
As hundreds of frightened children huddled in classrooms at Ronald E. McNair Discovery Learning Academy in Decatur, Antoinette Tuff stepped up -- and later recalled to ABC News how she'd deftly disarmed the suspect, Michael Brandon Hill, with prayer and a simple human connection.
"He said that no one loved him, and I told him that I loved him and that it was going to be OK, that we were going to get out safely," she told the network Tuesday, hours after police had taken the 20-year-old suspect into custody following the afternoon incident outside of Atlanta.
True to Tuff's words, no one was injured, even though authorities say Hill fired one round into the floor of the school's offices, then went outside exchange gunfire with approaching police.
Law enforcement officers responded to the scene quickly, and the school's leadership "did exactly what they were trained to do," DeKalb County Police Chief Cedric Alexander said Wednesday.
Still, even with their admirable efforts, Alexander admitted the situation could have turned out much, much worse were it not for the "cool, ... calm" and courageous school employee, whom he hailed a "real hero."
"She was in there, she was able to talk him down," Alexander said. "Had that not been the case, this could have certainly turned into something very ugly, very quickly."
Meanwhile, Hill remained jailed Wednesday, facing charges including aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon, police spokeswoman Mekka Parish said.
Ray Davis, the county police department's lead detective on the case, added Wednesday that Hill also will likely face a count of false imprisonment and "several weapons charges," while noting that authorities are still hammering out the exact nature and number of charges. Meanwhile, authorities are digging into his past.
That includes what Davis described as a criminal history that, while not "lengthy," did include incidents of violence.
He is on probation from a July conviction for threatening to kill his brother in a text message in neighboring Henry County in late December, that county's prosecutor, James Wright, said Wednesday.
He also was ordered to attend anger management classes, according to Henry County court records. It's not clear whether Hill started the classes. Wright said there is no indication that he completed them.
As to his connection to the school, why he might have gone into it armed and what he planned to do once there, authorities have not outlined a motive.
Beyond being from DeKalb County, Hill "possibly had been (at the school) there before speaking with some people in the administration," Davis said. But "there's no indication he had a grievance with the school." But did Hill go into the school intent on killing people?
Davis responded: "I believe there was something else, but I don't want to go into detail."
While what at first appeared to be another gut-wrenching school crisis ended as well as anyone could have hoped, the outcome didn't always seem so certain, Tuff told ABC.
She told the network that Hill sent a teacher who had been in the front office out to tell school employees that a shooter was in the building, and told her to call police and the media.
According to school district spokesman Quinn Hudson, three employees witnessed what happened in the front office. He did not name any of them, but Tuff spoke openly to ABC about her experiences along with two police officers who helped arrest Hill.
"I began to speak with him at that time, but he would not say anything," she said. "He just wanted me to know he was not playing and for me to call the news and also the police to let everyone know he was here."
Police did respond in force "very, very quickly" -- including some officers who took up positions with long rifles -- "to engage the threat" and prepare for the worst, said Alexander.
"We can all make a a reasonable assumption that he came there to do some harm," the police chief said, recalling last year's school massacre in Connecticut that ended with 20 students, six adults and gunman Adam Lanza dead. "He entered a school, an elementary school with children in it ... to do one of two things: Either to do harm to those children and/or any first responders."
Thankfully, that didn't happen.
In fact, the suspect never went beyond the school's offices, and never near its classrooms.
But he did open fire -- first by shooting into the office's floor, then going outside a few times to shoot at approaching law enforcement officers. Davis said that one officer did return fire.
That was when Tuff entered the picture, by trying to connect with the gunman. She began to talk about her own life experience, she told ABC, "to get him to be able to start talking with me and opening up."
The suspect told investigators that he'd been on unnamed medication, "and that he stopped taking it," Davis said.
Tuff said he told her as much as well, "and that he was going to die anyway and that he was OK with dying and that he was going to kill all of the police officers."
"And that he wanted me to know that he was not going to hurt me," she said. "And I told him OK, and that it was going to be OK."
Tuff said she encouraged Hill to surrender and offered to stay with him until police arrived. When he agreed, she said she helped him unpack his extra ammunition before officers came.
What sustained Tuff through such an ordeal? Prayer, she says.
"I just prayed the whole time," she told ABC.
So what's next?
The investigation, for one, continues. Police have learned that Hill got the "AK-47 type assault rifle" -- which he apparently took a photo of himself with -- "from the house of an acquaintance," said Davis, who did not say whether it was stolen.
On Wednesday, authorities were still trying to track down that acquaintance, as well as the person who originally bought the gun.
While there initially were fears that the suspect also had explosives, further tests indicate that was not the case: He came in with the rifle, a bag of ammunition and nothing else harmful.