JEFFERSON COUNTY, Colo. - Firefighters were called to Columbine High School early Thursday morning. Inside they found smoke.
Littleton Fire Division Chief Wayne Zygowicz said the smoke came from a drying fan that malfunctioned.
Eight units from the Littleton Fire Department helped ventilate the building at 3:15 a.m.
Dispatchers initially told 7NEWS there was a small fire in a classroom, but Zygowicz said there was no fire.
A fire last Wednesday at the school was caused by contractors who were welding on the roof of the school, catching insulation in a wall on fire.
The smoke on Thursday was caused by a cleaning crew working on the school's floors.