Officials in Chardon, Ohio, outside Cleveland, say there was no reason a 17-year-old shot five other students on Monday.
They say the suspect, TJ Lane, didn't know them.
Three of the wounded students have died. One other victim is still in serious condition.
Accused gunman TJ Lane arrived for his first court appearance Tuesday shielded by a heavy bulletproof vest.
Inside, Lane sat out of camera range with his grandfather and two aunts.
Prosecutors say they'll likely charge Lane as an adult with three counts of aggravated murder for Monday's deadly rampage.
The 911 calls from that day have been released:
Dispatcher: "911, where is your emergency?"
Caller: "We just had... we just had a shooting at our school. We need to get out of here. Oh my God!"
Dispatcher: "OK. OK, ma'am. (We've got a school shooting) Ma'am, what school?"
Caller: "Chardon High School."
The tapes captured the terrifying scene as it unfolded.
Caller: "Yes, yes. I'm a student. I was right by the shooter when he pulled the gun."
Dispatcher: "OK. Who was the shooter?"
Caller:"Uh, his name is Thomas Lane."
Geauga County Prosecutor David Joyce says Lane has admitted taking a .22 caliber pistol and a knife into the school, and pulling the trigger ten times.
"He chose his victims at random," Joyce says. "This is not about bullying. This is not about drugs."
Three victims - - Russell King Jr., Demetrius Hewlin and Danny Parmertor died. Two others were injured, including 18-year-old Joy Rickers, who was released from the hospital Tuesday.
Assistant Football Coach Frank Hall is being credited with saving lives when he chased Lane out of the school. "Chardon's always been great. It's gonna be great. I just want to thank everybody for their thoughts and prayers," he says.
Last night, thousands of residents in the tight knit community gathered once again to remember the victims.
"Just coming together as a group," said one person at the gathering, "coming together in the same spirit. What better way is there than to begin the healing?"
School will be open Wednesday for students and staff to seek grief counseling. Classes are slated to resume Thursday.
To see Michelle Miller's report, which includes the audio of the 911 calls, click on the video in the player above.