FRIENDSVILLE, Tenn. (WATE) — Students at Union Grove Elementary School are safe after they were evacuated during a fire drill Thursday morning due to smoke in the building, according to a Blount County Schools spokesperson.

Initially, the students were evacuated to the school’s gymnasium and were all safe, BCS supervisor of instruction and district communications Amanda Hill Vance shared in an email that went out to parents. Soon after, students and staff were able to return to the building after an all-clear from emergency personnel.

The smoke in the building was caused by a burnt belt of a heating, ventilation and air conditioning or HVAC unit.

Students are resuming their normal instructional day, Vance said in an email update Thursday.