Crews responded to a house fire on Wilson Avenue near Dennett just before 10 a.m.Tuesday.
When firefighters arrived, they found a large fire in the backyard of a house with multiple cars, a shed and fences.
The fire spread to a neighboring home, which was also damaged.
One firefighter was injured after part of the ceiling fell on him. A total of 40 firefighters responded to battle the flames.
Authorities believe the fire started in the backyard but have not determined what caused the fire.