LAKEWOOD, Colo. -- Investigators said Wednesday that the fire inside the small gym at Bear Creek High School was the result of arson.

The fire forced the evacuation and closure of the school Tuesday morning. School officials said there will be no school the rest of the week and no school on Monday.

The small gym area suffered structural damage as a result of the two-alarm blaze and a beam in the ceiling has to be installed to keep it safe, authorities said.

Crews on Wednesday spent the day cleaning up areas damaged by smoke and flames.

No dollar amount estimates are available yet.

School administrators say they'll notify parents when it's safe for students to pick up their belongings.

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