LIMA, Ohio (AP) — The convicted killer of three Ohio students at a high school cafeteria escaped from a prison Thursday night and a search was underway in northwest Ohio, police said.

Nineteen-year-old T.J. Lane escaped along with two other inmates from Allen Correctional Institution in Lima, about 80 miles south of Toledo, and one of the inmates was captured, Lima police Sgt. Andy Green said.

A search was underway in woods and a residential area near the prison, Green said, and the two escapees are considered dangerous.

Authorities said they do not believe the two men were armed, however. They had no further information on how the inmates escaped from prison. Green said the police were notified about 8 p.m. Thursday evening.

Lane, then 18, pleaded guilty last year to shooting three students in February 2012 at Chardon High School, east of Cleveland. He said he didn’t know why he did. At his sentencing, he unbuttoned his dress shirt to reveal his T-shirt reading “killer”; he cursed and gestured obscenely as he was given three life sentences.

Chardon Superintendent Michael Hanlon said the school continues to monitor the situation and will offer counseling throughout the school day Friday if school is in session.

Authorities identified the other inmate as Clifford E. Opperud, 45, and said he was serving a sentence for aggravated robbery, burglary, and kidnapping.

Prosecutors say Lane took a .22-caliber pistol and a knife to the school and fired 10 shots at a group of students in the cafeteria. Daniel Parmertor and Demetrius Hewlin, both 16, and Russell King Jr., 17, were killed.

Lane was at Chardon waiting for a bus to the alternative school he attended, for students who haven’t done well in traditional settings.

Before Lane’s case went to adult court in 2012, a juvenile court judge ruled that Lane was mentally competent to stand trial despite evidence he suffers from hallucinations, psychosis and fantasies. At his sentencing, Lane was defiant, smiling and smirking throughout, including while four relatives of the victims spoke.

Reached Thursday at her home in Chardon, Dina Parmertor, mother of Daniel Parmertor, said of Lane’s escape: “I’m disgusted that it happened. I’m extremely scared and panic stricken. I can’t believe it.”

Ohio public safety and correction officials said they began an “extensive search,” along with the local authorities and the Ohio State Highway Patrol after the inmates escaped at 7:40 p.m. Thursday from the Allen Oakwood Correctional Institution.

“All available troopers from the Ohio State Highway Patrol have been joined by Allen County Sheriff’s deputies and local area law enforcement in establishing a perimeter and searching the area,” Ohio Department of Public Safety Director John Born said. “A Patrol helicopter with advanced infrared detection equipment has been deployed and is engaged in the search as well.

Born encouraged the public to call 911 of any suspicious persons or possible sightings.