Eighteen-year-old T.J. Lane was sentenced Tuesday in Chardon. At the proceeding, he was wearing a white T-shirt with "killer" scrawled across it in large, apparently handwritten letters.
Lane has admitted firing 10 shots last year at students at Chardon High School, east of Cleveland. He had been waiting for a bus to his alternative school.
Investigators say Lane said he didn't know why he did it.
Lane was charged in adult court but wasn't eligible for the death penalty because he was 17 at the time of the shootings.
Killed were teenagers Russell King Jr., Daniel Parmertor and Demetrius Hewlin.