Hebron High School School in Carrollton was evacuated Monday afternoon, after a heating unit malfunctioned, causing smoke to enter a building, officials say.
Firefighters were called to the campus at about noon due the smokey odor, according to Liz Hawes with Lewisville ISD.
Students were moved to the Hebron 9th grade campus nearby.
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Due to the incident, the 10th, 11th and 12th grade classes were dismissed at 2:15 p.m.
Buses will run at their normal times and pickup at their normal locations.
Ninth grade classes were not interrupted and will be released on time at 3:30 p.m.
No injuries were reported.