Authorities have caught the convicted killer of three Ohio students hours after he escaped from prison.

TJ Lane (19) was found early on Friday, the Ohio State Highway Patrol said.

Lane escaped along with two other inmates from a prison in Lima, about 130kms south of Toledo, setting off a search by law enforcement officials using a helicopter and infrared-detection equipment.

One of the inmates was captured quickly. The other one, Clifford E Opperud (45), is apparently still at large.

"We got him," Lima police tweeted in the early morning hours, referring to Lane.

"One more to go."

The circumstances of the inmates' escape from the facility with more than 1,600 prisoners were not immediately known.

Lane pleaded guilty last year to shooting three students in February 2012 at Chardon High School, east of Cleveland.

He said he did not know why he did. At his sentencing, he unbuttoned his dress shirt to reveal his T-shirt reading "killer".

As he was given three life sentences, he cursed and gestured obscenely.

Prosecutors say Lane took a .22-calibre 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.

Another student was left paralysed from the waist down.

While he was at large, authorities had warned that Lane was dangerous, warning residents not to let strangers into their homes or to pick up hitchhikers.