The fire was reported at about 3:05 p.m. at 3796 Bertini Court, fire Capt. Chuck Rangel said. It was controlled at 4 p.m.
Two of the four units were affected, he said.
The fire appears to have started in the bedroom of a downstairs unit and spread to the unit directly above it, burning the ceiling of the downstairs unit and the floor of the second-level unit, Rangel said.
Those two units will be temporarily uninhabitable, he said.
No one was injured in the fire.
The cause of the blaze is under investigation.