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.