(CNN) -- About a week after an Ohio judge ruled that he could be tried as an adult, T.J. Lane, 17, was indicted in the shooting deaths of three classmates at Chardon High School.
Lane was indicted by a grand jury on three counts of aggravated murder, two counts of attempted aggravated murder and one count of felonious assault, according to court documents from Geauga County, Ohio, dated May 30.
On Tuesday, prosecutors released the documents to the public.
Authorities allege that on February 27, Lane walked up to a table in the Chardon High School cafeteria and started firing.
"He was silent the entire time," said Nate Mueller, who was a few feet away. "There was no warning or anything. He just opened fire."
A teacher identified as Frank Hall helped chase the gunman out of the school. Police arrested Lane a short time later.
When the violence ended, six students had been shot, and in the following days, three died: Daniel Parmertor, 16; Demetrius Hewlin, 16; and Russell King Jr., 17.
Days after the attack, prosecutor David Joyce said that Lane admitted taking a .22-caliber gun and a knife into Chardon High School that morning and firing 10 rounds, choosing his victims randomly.
"We've had to deal with murders before, but none on this scale, and certainly not involving a high school," Joyce said Tuesday.
Joyce said that in the months since the bloodshed, he has met with the families of the victims on a "constant basis," adding, "Their child was murdered. Justice for them would be to see Mr. Lane detained for an extended period of time."
Lane's attorneys, Ian Friedman and Mark DeVan, said they were unable to comment Tuesday.
On May 24, Geauga County Judge Timothy Grendell ruled that Lane could be tried as an adult, but federal law prohibits capital punishment for anyone under the age of 18.
"Obviously, he can't be put to death as a juvenile, but he can certainly be sentenced to life without parole," Joyce said, "That's up to a jury to decide."
Lane will be arraigned in Geauga County Court of Common Pleas before Judge Forrest Burt at 1:30 p.m. Friday.