Firefighters responded to the 8200 block of Joshua Circle around 10:30 p.m. Crews say flames quickly spread from the home's roof to the attic.
Amit Desai, who lives across the street, said his family was having dinner when his kids alerted him to the fire.
"So we ran, me and my wife," he said.
Desai said they ran inside the house to help his neighbor escape.
It took firefighters less than an hour to knock out the blaze. Crews were able to keep the flames from damaging other houses. No injuries were reported.
Investigators found remains of bottle rockets scattered around the scene.
"You have a couple of different factors here. First, you have the use of illegal fireworks, which we warn people not to do, and second of all, we've got a shake-shingle roof that's dry and brittle," said Kris Concepcion of the Orange County Fire Authority.
The house has been red-tagged due to heavy damage. Neighbors say Friday is the homeowners' 39th wedding anniversary. According to fire investigators, the damage to the structure is estimated at $135,000, while the damage to contents is estimated at $65,000.
Authorities are trying to determine who shot off the bottle rockets. The investigation into the incident is ongoing.