We talked to one student who was in the classroom.
In the front row.
And who tells us tonight, she's just thankful to be alive.
"He had the gun at my head and was saying, if you say one more word, you will be dead," says NCHS student Mackenzie Baker.
It was supposed to be a typical day in health class for the students at Normal Community High School.
"We had like 10 or 5 minutes left of class."
And that's when Mackenzie Baker says she realized it was about to be anything but. "I was writing something down and I looked up and he was playing with a gun. He clicked it and the bullet fell on the floor. At that time, I didn't realize, like this is real."
She says the next moments for the students were a blur.
Then the bell rang for passing period.
"That's when he went over and opened the door and was waving the gun around out in the hallway and asking if anyone wanted to come in here and die today."
When a group of kids got up to comfort an upset student in the room, that's when Mackenzie said they made their move.
"I heard somebody whisper behind me, dude, the door's unlocked. We can make a run for it. And before I could even process what was happening, I was running down the hallway with a bunch of other kids that had ran out of the room and he had, I heard gunshots, but I never looked back," Baker explains. "I know if he would've been able to control the gun, one of us would've been shot."
Mackenzie says she knows she's lucky to be alive
As for the kids back in the classroom...
"He had them all up against the wall," Baker says.
She knows a teacher saved their lives
"Mr. S definitely saved everyone in there."
Mackenzie says this Friday is something she'll never forget.
And, especially for a young student, there's still a lot to process.
But as she looks back on the day, there is one message she wants to send.
"I do hope that this boy who brought this gun to school finds help and his family and everything is ok. Because I have no way to judge what he's going through. I don't want to offend anybody," Baker adds. "But I do hope everything works out and he's OK."