ATLANTA (CNN) -- A man slips behind someone else into a packed elementary school with an AK-47-type weapon. He goes into the office and shoots at the ground, then darts between there and outside to fire at approaching police.

So what do you do?

If you're Antoinette Tuff, who works in the front office at Ronald E. McNair Discovery Learning Academy just outside Atlanta, you don't run. You talk. You divulge your personal struggles to the gunman, you tell him you love him, you even proactively offer to walk outside with him to surrender so police won't shoot.

And then the nightmare ends -- with the suspect, later identified as Michael Brandon Hill, taken into custody and no one inside or outside the Decatur school even hurt, despite the gunfire.

"Let me tell you something, babe," Tuff tells the dispatcher at the end of the dramatic 911 call, obtained by CNN affiliate WXIA, that recounts her minutes of valor and terror. "I've never been so scared in all the days of my life. Oh, Jesus."

This brief outburst of emotion, moments after police entered the school Tuesday, was in stark contrast to her cool, calm demeanor as heard earlier on that 911 call.

As a go-between, she relayed his demands that police refrain from using their radios and "stop all movement," or else the suspect would shoot. By the end -- with police themselves having never directly talked to him -- Tuff and the gunman were talking about where he would put his weapon, how he'd empty his pockets and where he'd lie down before authorities could get him.

On Wednesday, a day after the ordeal, DeKalb County Police Chief Cedric Alexander hailed the school employee as a "real hero." Nearly nine months after the horrific massacre at Sandy Hook Elementary School, Tuff treated the gunman in her school -- who admittedly was "not mentally stable" and had about 500 rounds of ammunition -- as a person first, and a suspect second.

No one wants to think about what might have happened had she, or the shooter, acted differently.

"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, very ugly very quickly."

Tuff, others 'thought it was a drill'

Tuff had training in how to deal with such a scenario.

School staff regularly train for dangerous situations involving trespassers and emergency protocol, school district spokesman Quinn Hudson said.

Tuff and two other staff members -- a cafeteria manager and a media specialist -- were specifically trained in hostile situations.

"The training is so often and extensive, they thought it was a drill" at first, said Hudson.

While Tuff worked to keep the gunman calm and spoke with him, she signaled a code to her two counterparts, who immediately triggered a phone tree to tell teachers to lock doors and send children to safety, Hudson said.

"Her name, Antoinette Tuff, says everything about her," said Brian Bolden, the school principal. "Tough. She has always been that way, from the first time I met her."

He describes her as a strong leader whose authority everyone respects.

She has been with the school system eight years -- the past three at McNair.

And she almost wasn't there Tuesday. Tuff was scheduled to be off that day, but because of a shift change, she ended up right where the school needed her to be.

She is out of school all week, recovering from prescheduled surgery.

Inside the suspect's mind

On Wednesday night, Hill, 20, was in a Georgia jail awaiting a still undetermined initial court appearance.

Authorities are still hammering out exactly what charges he will face. Police spokeswoman Mekka Parish has said they would include aggravated assault on a police officer, terroristic threats and possession of a firearm by a convicted felon. Ray Davis, the lead detective on the case, added that false imprisonment and "several weapons charges" probably will be included as well.

Whenever the charges come down, Hill will waive his initial court appearance, said Claudia Saari, public defender for the Stone Mountain Judicial Circuit. She said members of her office's mental health division are handling his case, declining to make any further comment.

This week's incident is not Hill's first run-in with the law. He has a criminal history in DeKalb and neighboring Henry County that, while not "lengthy," does include violence, Davis said.

Specifically, Hill pleaded guilty in July to making "terroristic threats and acts" against his brother.

Henry County court records show that, in addition to three years of probation, he was ordered to attend anger management classes. But that county's district attorney, James Wright, said Wednesday that there's no indication that Hill completed them.

As to any connection to McNair Discovery Learning Academy, why he might have gone into it armed, and what he planned to do once there, authorities have not outlined a motive or a detailed plan.

Being from DeKalb County, Hill "possibly had been there (at the school) before speaking with some people in the administration," Davis said. But "there's no indication he had a grievance with the school."

Before he entered the school, the suspect took a picture of himself with the assault rifle -- which he'd taken "from the house of an acquaintance," said Davis, who did not say whether the weapon was stolen.

So did Hill go in intent on killing people?

Davis responded: "I believe there was something else, but I don't want to go into detail."

Some clues about his mindset are evident in the dramatic 911 call.

With Tuff acting as the intermediary on the call, the suspect said that "he should have just went to the mental hospital instead of doing this, because he's not on his medication,"

The gunman, again via Tuff, insists he wants nothing to do with the school's students, "he wants the police."

The school worker then adds, "He said he don't care if he dies, he don't have nothing to live for."

Chief: It 'absolutely' could have been 'another Sandy Hook'

While Tuff seemingly kept her cool inside the school, a swarm of law enforcement was springing into action outside.

Police reacted "very, very quickly" -- including some officers who took up positions with long rifles -- "to engage the threat" and prepare for the worst, said Alexander, the DeKalb County police chief.

"We can all make a reasonable assumption that he came there to do some harm," he 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. While he fired some rounds at police -- and one officer shot back at him -- no one was hit outside either.

And while there initially were fears that the suspect also had explosives, further tests indicated that was not the case: He came in with the rifle and a bag of ammunition, but no explosives.

Community members and leaders are offering praise for Tuff and police, as well as gratitude that the story did not turn tragic.

"Was the potential there to have another Sandy Hook?" admits Alexander, the police chief. "Absolutely."

CNN's Josh Levs, Tristan Smith, Michael Pearson, David Mattingly, Joe Sutton and Marylynn Ryan contributed to this report.