Lane was also charged in Geauga County Juvenile Court with two counts of attempted aggravated murder and a single count of felonious assault, The (Cleveland) Plain Dealer reported.
The teenager is accused of bringing a .22-caliber handgun to school Monday morning. He allegedly opened fire on several students, fatally wounding Danny Parmertor, 16, Russell King Jr., 17, and Demetrius Hewlin, 16.
Two other students were wounded. Joy Rickers has been released from the hospital and the other, Nick Walczak, 17, was paralyzed and has bullets in his cheek and neck, ABC reported.
At an initial appearance in juvenile court Tuesday, Geauga County Prosecutor David Joyce told a judge Lane admitted shooting the students, whom he had picked at random, The Plain Dealer reported.
The newspaper said an arraignment is set for next week, and Lane likely will be tried as an adult, though as a minor he will not face the death penalty.
During a news conference in which officials announced the charges, Assistant Chardon High football Coach Frank Hall said he was no hero, The Plain Dealer said. Hall risked his life by chasing a gunman from the school during the Monday attack.
Also Thursday, about 1,000 people marched from a historic square in Chardon to the school in a show of solidarity.
Students were coming back to the school for the first time since the shootings Monday, The Plain Dealer reported.
"We're together in this. We don't need to be afraid because we have each other," freshman Jorian DeFelice said. At a bandstand along the route of the half-mile march, a girl told the crowd, "We are one school, one town, one heartbeat."
Two girls at the bandstand, which has become a shrine with signs and flowers, also offered a brief prayer, the newspaper said.
A large crowd near the school, as well as drivers waiting in traffic, began to applaud the marchers.
President Barack Obama called Chardon High School principal Andy Fetchik Wednesday to offer condolences to the school and community, The Plain Dealer reported. A White House official said Obama was heartbroken and asked how the principal and the school community were doing.
Court records indicated Lane has a disorderly conduct conviction as a juvenile and was sentenced to as long as 30 days in a detention center, fined and ordered to complete 24 hours of community service, CNN said. He also recently had his driver's license reinstated after it was suspended for 2 1/2 months for a ticket.
Classmates said Lane had a tough childhood. The Plain Dealer reported both of his parents have been charged with domestic violence against each other and his father had served time for assaulting a police officer, among other things.
"I think there's a lot of kids that go through things like that. That doesn't give them the right to kill other people," Bob Parmertor, Daniel Parmertor's grandfather, told CNN. "They're five families including ours that have been affected by this. No one has the right to shoot other people because they've had a rough life."
Classes in the suburban Cleveland community are scheduled resume Friday.