OWINGS MILLS, Md. (WJZ) — A police trainee remains hospitalized after being shot in the head during a training exercise.

Our WJZ investigation continues to reveal new information about exactly how it happened. There are now concerns that the training session was fully staffed.

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Mike Hellgren keeps digging into this story.

Sources tell WJZ there were not enough people monitoring the training. That officer is in critical condition after several surgeries.

The police training session where an officer was shot in the head was not properly staffed, according to WJZ sources.

As part of our investigation, WJZ has also learned the training officer–William Scott Kern–who Baltimore City Police confirm pulled the trigger, was frustrated the trainee kept raising his head when he should have remained hidden. Kern put his weapon up to a glass window and fired. He thought he was using a fake weapon with simulator bullets. Instead, it was his real service weapon with live ammo.

Lieutenant Gene Ryan with the Fraternal Order of Police worked with Kern.

“We both taught self-defense. He was one of the excellent instructors out there. His work ethic is impeccable. As a street cop, it was no different,” said Ryan. “This one time, just to take that one second back, it’s got to be devastating.”

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Sources tell WJZ there were only two training officers present, but there should have been four.

“Were they redeployed other places? Should there have been more instructors at that site where the exercise was being carried on?” Ryan asked.

Training remains suspended. The mayor has said she was so angry about this, she was speechless.

City Council members are outraged–stressing the importance of finding out what happened.

“It would seem to me that someone didn’t follow the rules,” said Councilman Carl Stokes. “There’s obviously a laxity of procedure and action in this particular case.”

“All that has to be looked at from A-to-Z. All the protocol, the training, the types of training that they do,” said Councilman Brandon Scott. “We will ensure we do everything in our power to make sure this never happens again.”

State police say their investigation will take several weeks to complete.

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WJZ’s media partner the Baltimore Sun is reporting the Baltimore City Police Department is refusing to release its training policy.