Asheville firefighters responded to Oakley Elementary School in Asheville on Monday morning.
Crews arrived on scene and found heavy smoke inside a classroom on the first floor shortly after 8 a.m.
Asheville Fire Department Public Information Officer Kelley Klope told News 13 conditions worsened while crews were on scene.
There was not a fire, but officials say the smoke was generated by a malfunction with the HVAC blower motor for room 102.
Everyone in the building was evacuated for a short period of time. They have since been allowed back inside the building.
Klope said maintenance personnel are at the school replacing parts.
No injuries have been reported, according to officials.