Nitro Elementary has dismissed all students for the day because carbon monoxide was detected in one wing of the school, an emergency official said.
There were no illnesses, injuries or complaints reported.
Kanawha County Deputy Emergency Services Director C.W. Sigman said that a heating unit on the roof was the cause of the carbon monoxide leak.
Sigman said that the school turned the unit off, and evacuated all students into another wing of the school.
Nitro Fire Department has been on the scene monitoring carbon monoxide levels. They have detected the gas in two rooms, both of which have been evacuated.
Superintendent Ron Duerring made the decision to dismiss students, Sigman said.
The school is notifying parents and arranging for buses to take students home.