Ottawa firefighters are being credited with saving a historic building after a blaze erupted early Saturday at the Carp fairgrounds in the city's west.

Callers to 911 reported seeing smoke and flames coming from the roof of the fair's agricultural hall at about 3:30 a.m.

Fire officials said their crews managed to contain the fire to the second floor office and meeting rooms as well as the attic.

Though the damage is estimated to reach $100,000, officials said, the barn's historic features were largely spared.

A gas-fired wall heater sparked the blaze, firefighters said..

The 149th annual Carp Fair is slated for September.