An aviation technical school operating at the Youngstown-Warren Regional Airport is closed as local and state officials conduct an investigation into an accident Wednesday that hurt two students.

The accident happened inside of a classroom at the Pittsburgh Institute of Aeronautics, which operates at the airport.

The students — identified in a police report as 20-year-old Zachary Norris, of Youngstown, and 28-year-old Cody Keller, of New Castle — were working on an engine when the accident happened.

Norris was hit in the head with a propeller when the motor fired off, knocking him unconscious. He was taken to the hospital with severe injuries and remains in critical condition.

“I think St. Elizabeth Hospital has done a phenomenal job, considering what I saw and, in my experience, I saw what I believe to be a pretty serious, critical incident,” said Vienna Township Police Chief Bob Ludt.

Keller was also taken to the hospital but has since been released. He suffered a broken hand.

Investigators are still trying to figure out how it happened.

“We’re still putting it all together as to exactly the sequence of events,” Ludt said.

He said from their investigation so far, the two students were following procedure before starting the engine outside by turning the propeller circulating the oil in the motor.

“Apparently, those engines are very sensitive, and there must have been enough fumes or fuel in the system that as they were turning it, the engine fired off.”

Suzanne Markel, president and CEO of Pittsburgh Institute of Aeronautics, released the following statement:

We are extremely grateful for the rapid response by 911 and the EMTs on site.

We are not able to comment on the extent of the students’ injuries at this time.

PIA is committed to a safe learning environment for all students and staff. Today’s incident reinforces the crucial importance of this mission. We will be conducting a full investigation into what happened today, and will be cooperating fully with all appropriate authorities.

The Youngstown campus is currently closed and will also be closed tomorrow, March 28th, in order that these activities may continue without interruption or delay.

The students involved and their families are in our hearts as we wait for more information to become available.

“It was a freak accident. The fact that the engine fired off when…they’ve probably done that many times and it never happened. They were pretty confident, apparently, that it wasn’t going to fire off and it did,” Ludt said.

He said they want to get to the bottom of how this happened to help the school prevent it in the future.