LAKEWOOD, Colo. -- Two 15-year-old students at Bear Creek High School are suspected of starting a fire in the school's small gym that resulted in the evacuation and closure of the school, Lakewood police said.

The boys live in Lakewood and have been arrested on felony charges of first- and second-degree arson, police said. Their names are not being released because they are juveniles.

Cindy Matthews, spokeswoman for West Metro Fire said evidence at the scene and dozens of interviews led to the arrests.

One was taken into custody on Wednesday and the other on Thursday, according to Matthews.

Fire investigators aren’t discussing specifics about the fire, or what the boy’s intentions may have been, citing privacy laws when juveniles are involved.

“Unfortunately we can’t release what the boys may have used to start the fire or what may have caught fire,” Matthews said.

The fire broke out in the small gym just before noon on Tuesday. There was no class scheduled in the gym at the time of the fire, and investigators believed the blaze was the result of arson.

It took firefighters about 25 minutes to put the fire out. Investigators said combustible materials in the gym caught fire, causing extensive damage to the building and school.

Students attending a baseball game at the school Thursday told 7NEWS there is a lot of talk going around about what may have happened.

“I’ve heard everything from someone lit a firework to someone had a cigarette,” said Brian Clark, a student at Bear Creek.

Fellow classmate Erik Mattingor said he didn’t know either boy suspected in the crime.

“The day it happened I heard there were freshman in the small gym lighting the carpet on fire,” Mattingor said.

The school has been closed since the fire because of the smoke damage, and classes are canceled through Monday. Juniors had to go to Green Mountain High School on Wednesday to take their state-mandated ACTs.

No injuries were reported. Most of the school evacuated when the fire alarm sounded.

There is no damage estimate on the fire. School administrators said they'll notify parents when it's safe for students to pick up their belongings, which they abandoned inside the classrooms when they evacuated.

Athletic activities and Friday night's prom will happen as scheduled.

Authorities were awaiting the result of air-quality tests before deciding whether the school could reopen Monday. Bear Creek has 1,865 students.