Authorities are trying to figure out why a well-respected physical education teacher was found shirtless and armed inside his east Alabama high school after having set fire to the building Thursday morning.

Just before 8 a.m. Thursday, Saks High School Principal Seth Taylor was doing his morning rounds when he noticed smoke coming from the gym, said Calhoun County Sheriff Matthew Wade.

When the principal went to investigate, he saw several windows had been broken.

As he was examining the broken windows, Wade said, the door opened behind Taylor and it was longtime P.E. teacher LaGregory Thomas, 38, of Anniston.

Thomas was shirtless and holding a pistol, the sheriff said.

Smoke was coming from behind Thomas where a fire had been set in that room.

“The principal could tell by the things he was saying that he wasn’t in a good frame of mind or mental status,’’ Wade said.

“The principal, I can’t speak highly enough of how he handled himself, was able to get the teacher to put the weapon down and get him away from it and notify the SRO,’’ he said.

“There was no violent, no threats of violence,” Wade said. “It’s just a weird situation that was very dangerous.”

Wade said it appeared Thomas had been in the school for hours before he was discovered by the principal.

There had been no prior incidents with Thomas, or any sign that something was amiss.

“This is a long-term teacher and they said he was a good guy,’’ Wade said. “The SRO knew him personally and said, ‘I’ve never seen him act this way or talk this way. He’s a great guy.’”

“We hate that we even have to tell this story,’’ the sheriff said, “but when kids are involved, and this kind of thing happens, it’s important that the public know about it.”

“There’s no sign he is a bad person or had bad intent,’’ he said. “But even though he might not have had bad intent, it’s still a dangerous situation for the school to be put in.”

Wade said they were obtaining search warrants as part of the probe, including for Thomas’s house and to be able to take a blood sample from him.

“He’s definitely not in his right mind,’’ he said. “His mental status is not what is what it has been in the past. Things he is saying and doing seem to point toward his mental health. Why? We don’t know, but we’re going to try to find out.”

Thomas was undergoing booking Thursday afternoon at the Calhoun County Jail on a charge of second-degree arson. He will be taken to a hospital at some point.”

“It’s just as important to us to find out why,’’ Wade said. “It’s not as simple as, ‘You started a fire, we’re going to take you to jail.”

“Our goal,’’ he said, “is to protect those kids as best we can.”