Brandon Stehl was sitting in the gym at Dixon High School, learning about how he would receive his cap and gown for graduation, when he said heard gunshots ring out.
"All of a sudden out of nowhere you just hear pop pop pop!" Stehl said. "Sounds like firecrackers, and then there's dead silence. Then, all of a sudden, a teacher comes in and says, 'Go go go go!' and everybody floods out of the school, running over to pizzeria."
The gunshots were from an armed suspect, who was wounded in a shootout with police at the school, authorities confirmed.
According to Dixon Police Chief Steve Howell, a school resource officer "confronted an armed male subject" around 8 a.m. at Dixon High School after several shots were reported fired near the school's west gym.
The armed teen fled from the responding officer, allegedly firing shots as he ran. The school resource officer returned fire, injuring the suspect, authorities said.
The injuries are believed to be non-life threatening and the suspect, identified only as a 19-year-old former student at the school, was taken into custody. No other injuries were reported.
Stehl, who officially graduated last year, said the suspected gunman was a former friend of his.
"He's never had any motives for shooting, I've never known him to be an evil person, he was never bullied and never bullied others," he said. "So this was a surprise. I'm glad he's alive...stupid."
Dixon High School and all Dixon public schools were placed on lockdown following the shooting. Dixon High School remained the only school on lockdown shortly after 11 a.m., though all students had been reunited with their parents, Howell said.
He noted that when police arrived at the scene, students and teachers were found barricaded in their classrooms, blocking doors with desks and bookshelves.
"A lot of things went right today when a great many of them could have gone wrong," said Dixon Mayor Liandro Arellano Jr.
Police said they believed the suspect "acted alone" and there was no further threat to students or staff. They thanked the officer who shot the suspect, praising him as a hero.
"With shots ringing out through the hallways of the school, he charged towards the suspect and confronted him head on," Howell said. "Because of his heroic actions, countless lives were saved. We are forever indebted to him for his service and his bravery."
Check back for more on this developing story.