Fire in a heating-air conditioning unit on the roof of Congregation Beth El forced evacuation of students in the synagogue's school wing Thursday afternoon, but the blaze was doused before causing significant damage.

Heavy smoke was coming from the Fairfield Woods Road structure when the incident was first reported about 1:45 p.m. Thursday.

Firefighters arriving on the scene discovered a fire in a natural gas-fed HVAC unit on the synagogue's roof, which had also created moderately smoky conditions inside. Students, who were evacuated before fire units arrived, were dismissed from classes early for the day, according to the fire report.

Fire personnel shut off gas to the building and contained the fire to the roof, where it was extinguished before spreading to other parts of the structure.

Firefighters also made sure that all of Beth El's religious artifacts and documents were protected during the operations.

In a statement issued after the fire, Assistant Fire Chief Scott Bisson said, "The school did an excellent job in exercising their fire-evacuation plan, which allowed them to account for each child outside of the school and kept the kids safely away from the school so firefighters could do their work."

There was no damage to the building, according to firefighters, and it was occupied immediately after the incident. A stretch of Fairfield Woods Road was shut down during the operation, but parents were granted access to the scene to pick up their children.

Southern Connecticut Gas personnel were dispatched to the scene to secure the broken gas line.

The fire is believed to be accidental, but remains under investigation by the Fire Marshal's Office.