At 10:50 p.m. Thursday, Portland Fire crews responded to a fire in the Sellwood neighborhood.
When they arrived at SE Glenwood and Milwaukie they found bushes on fire and the flames spread to a house.
The fire also caused a live power line to break free which was dangerous for firefighters.
The cause of the fire has been determined to be illegal fireworks. Witnesses said they saw an individual light a "mortar" round and throw it on the ground near the bushes.
All occupants and pets were evacuated safely.