REDLANDS (CBSLA/AP) — Investigators are trying to determine why a high school teacher started two small fires on campus while classes were in session.

Police say Timothy Mark Ridgway was arrested Friday on suspicion of arson at Redlands East Valley High School east of Los Angeles.

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The 59-year-old science teacher lit a hall pass on fire — the first of two fires he’s accused of setting in a building with 300 students inside.

“There was a burn on the wall but we didn’t think it was gonna be like super high,” said one of Ridgway’s students.

She says he didn’t say a thing when he lit the hall pass on fire – he just tossed the torched paper on his desk and calmly walked out. A couple minutes later, she smelled smoke.

“We hear the smoke alarm going off and he comes back in and says it’s not a big deal. We don’t have to evacuate,” the student said.

But the staff members who had to put out that fire might disagree.

The San Bernardino County Sheriff’s Department says Ridgway intentionally lit a poster on fire just outside the door.

They arrested him and charged him with felony arson.

“We were all asking him to go,” said the student. “We were all cheering him on and then he eventually agreed.”

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“We always thought he was a little bit weird like that but we just let it happen because we thought that was just his normal thing,” said the student.

Students say the poster Ridgway burned was for homecoming and that a spirit squad burst into his room just before and invited him to the homecoming game.

Now some wonder if that could have upset him.

“I don’t think he did it out of anger or anything. I think it was just a joke that got out of hand,” said student Matthew Barnett.

“Yeah he likes to joke around a lot. He’s a good guy,” said student Matt Casillas.

The Redlands Unified School District said in writing:

“This incident had no direct correlation to the instructional program and compromised the safety of our students…School staff, administration and the school resource officer worked together to extinguish the fire. Thankfully, no students were injured.”

Ridgway was immediately placed on administrative leave.

Ridgway’s bail was set at $250,000 and he’s schedule to appear in court Tuesday.

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