The fire burned through the two-story school, attached to Temple Israel of Great Neck at 108 Old Mill Road. Authorities say the flames started on the second floor of the Sondra and David S. Mack Religious School just after 6 a.m.
Heavy smoke billowed out of the school, and firefighters used tower ladders to break the glass and ventilate the building.
Police say the fire burned through a catering hall on the second floor and caused extensive smoke and water damage to the rest of the large building.
It took hours to bring the smoky fire under control. No injuries were reported, but all classes and other activities at Temple Israel in Great Neck were canceled.
The temple portion of the facility was not damaged. The conservative synagogue serves more than 1,000 families.
The cause of the fire is under investigation.
