Students ran for cover, while others were led to safety at nearby schools. He took out the first weapon and tried to fire it, but it jammed.
The suspect, identified by multiple students as Caleb Sharpe, was taken into custody by police and held in juvenile jail, the Spokesman-Review reported.
But the armed student wasn't swayed by those words and shot him.
The sheriff said the suspect fired more rounds down the hallway, striking the other students, before the custodian intervened, Knezovich said.
Authorities didn't release the suspect's identity or a possible motive.More news: Meet Alexis: Serena Williams' baby girl
The paper described an anxious scene outside Freeman, which reportedly has about 330 students, as parents gathered by caution tape trying to reach their children while a procession of emergency vehicles - law enforcement, firefighters and ambulances - surrounded the scene.
The student told the AP the suspect had been obsessed with past school shootings. "I came home and there was nothing that could stop the emotions", said Freeman High School junior Dylan Oja.
Stephanie Lutje told AP she was relieved to hear her son was safe after his school near Freeman High was put on lockdown.
Knezovich did not go into detail about how the rampage at the school in the town of Rockford ended, but he credited "some fairly courageous action by a member of the Freeman School staff".More news: Five Deaths, 100 Plus Evacuated From Nursing Home With No Power
Harper said the shooter had many friends and wasn't bullied, calling him "nice and amusing and weird".
"It was heartbreaking to hear that someone had died", Solsom said.
"I believe that what that'll do is help deter some of these potential killers from trying to commit crimes here in Arkansas", said Rep. Charlie Collins, (R) District 84. "You never think about something happening like this at a small school".
"As a school district that has been impacted by a similar senseless tragedy, we know Rockford has a long road to recovery ahead", Emily Wicks said in a statement on Wednesday.
That's when she said the girl had been shot in the back.More news: Hurricane Jose Continues Moving Slowly Eastward With Little Change In Strength