Students were screaming in panic in the dramatic calls.
T.J. Lane, 17, made his first court appearance Tuesday. He told police he did not target his victims when he fired 10 rounds into a crowd of students sitting at a cafeteria table at Chardon High School. Three people were killed and two others were injured.
Prosecutors described Lane as "someone who's not well," and said the shooting is not about bullying and didn't involve drugs. Lane was ordered to be held for the next 15 days.
Prosecutors have until Thursday to bring charges and are expected to ask that Lane be tried as an adult. He will probably be charged with three counts of aggravated murder and other offenses, officials said.
Authorities said Tuesday that Demetrius Hewlin, 16, and Russell King Jr., 17, died from their injuries. Daniel Parmertor, 16, died shortly after the shooting.
Hewlin attended Chardon High. King and Parmertor were students at the Auburn Career Center, a vocational school, and were waiting in the Chardon High cafeteria for their daily bus when they were shot.
Lane did not attend Chardon High but waited there for the bus to Lake Academy, a school for students with academic or behavioral problems.
An 18-year-old girl who was hurt in the shootings has been released from the hospital. The other injured person remains in serious condition.
Fellow students held a vigil Tuesday to remember all the victims. Classes are set to resume Friday at Chardon High School.
The Associated Press contributed to this story.