MATTOON, Ill. (WAND) - A fire at a Motel 6 in Mattoon was caused by a faulty air conditioner, WAND News has learned.

20 families were displaced, a firefighter was hospitalized, and a dog died as a result of the fire. 

The firefighter suffered dehydration, but has since been released from the hospital.

Flames erupted around 3 p.m. Thursday at the motel, located at Lake Land Boulevard and U.S. Route 45. Firefighters said Charleston and Lincoln volunteer firefighters responded to the scene to assist. 

The fire caused heavy damage to two or more Motel 6 rooms on the building's second floor.

The Mattoon Fire Department Chief told WAND News maintenance crews at the motel had switched out several AC units before the fire.

This was the third unit they had tried.