Students will not be in attendance at Dixon High School on Thursday as the investigation into the shooting at their graduation practice continues.
Roughly 180 students were in the school's gymnasium to practice for graduation at around 8 a.m. on Wednesday when authorities say 19-year-old Matthew Milby - one of the seniors graduating - came out of a bathroom with a gun and began shooting.
School resource officer Mark Dallas rushed at Milby, officials said, in an effort to protect the students - including his own son.
Senior Benny Roach was in the gym at the time and said he heard four or five loud bangs, then "what sounded like the resource officer yell, like, 'hey, stop.'"
As Milby was running away, authorities said he was firing at Dallas, who returned fire, striking Milby in the shoulder before arresting him.
"Oh his father's a hero," Roach said, adding, "so much more worse stuff would have happened today."
"He took it head on and went right after him," Roach continued. "He did his job."
As Dallas chased Milby, school officials said students were barricading themselves in classrooms as they had been trained to do, while others ran.
"(A) teacher peeks out of a doorway and he comes in and I seen his face he says, 'Everybody get out of here, go, go,” student Brandon Stehl recalled after the shooting.
"I’m still shocked now, even a few hours after the event my hands were still shaking,” Roach added.
School officials and law enforcement alike praised Dallas as a hero for his quick action, crediting him for saving countless lives.
"Our kids did a fantastic job, our staff did a fantastic job, our resource officer did a fantastic job," school principal Mike Grady said at a news conference. "It was a situation where this is the best possible outcome we could have."
The alleged gunman's mother Julie Milby said her son was bullied and that she had no idea he had the gun - which belonged to her but was kept at her 91-year-old grandfather's house - until after the shooting.
"I wouldn't have dreamed he would do this in a million years," she said, adding that before the shooting, her family was excited for Matthew Milby to graduate on Sunday.
Now, he is charged with three felony counts of aggravated discharge of a firearm and remains at an area hospital on 24-hour watch.
Once released, Illinois State Police said he will be taken to jail. His bond was set at $2 million.