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, Kendra McCray, at the end of the dramatic 911 call 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.
"He doesn't want the kids, he wants the police, so back off," she said in the call. "What else, sir? He said he don't care if he die, he don't have nothing to live for, and he said he's not mentally stable."
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.
"It's going to be all right, sweetie," she tells Hill at one point in the call. "I just want you to know I love you, though, OK? And I'm proud of you. That's a good thing that you're just giving up and don't worry about it. We all go through something in life."
Tuff then let the gunman know that she'd been down before herself, but she'd picked herself up. He could, too.
"I thought the same thing, you know, I tried to commit suicide last year after my husband left me," she said. "But look at me now. I'm still working and everything is OK."
That day, for everyone at that school, everything did turn out OK. Shots were fired, but no one got hurt. The gunman never made it to the classroom area, deciding instead to give up and lay down.
This ending is thanks largely to Tuff, said McCray, the woman who fielded her 911 call. Echoing President Barack Obama -- who called Tuff on Thursday to thank her -- and many others, McCray described Tuff as a "true hero" for being courageous, calm and personable.
"You did a great job," McCray said, shortly after the two met in person for the first time Thursday for an exclusive interview with CNN's Anderson Cooper. "You made my job a lot easier."
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.
The past eight years, Tuff has been with the Georgia school -- 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.
The school's existing safety procedures will remain the same while the investigation takes place, Bolden said.
But he promised any needed changes will happen. "We will do everything humanly possible in our power to keep this next generation of learners safe."
Counseling was made available to the kids, and the school understands that some children might not be ready to come back right away, he said.
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 and declined 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."
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? Absolutely," admits Alexander, the police chief.
CNN's Tristan Smith, Michael Pearson, David Mattingly, Joe Sutton and Marylynn Ryan contributed to this report.