The blaze was reported at about 2:35 p.m. on the top floor of a three-story building at 276 Jersey St. and then spread to a second building, fire spokeswoman Mindy Talmadge said.
Firefighters responded and extinguished the fire by 3:22 p.m., Talmadge said.
The blaze affected four units at the two buildings. The American Red Cross responded and is assisting the displaced residents, Talmadge said.
She said the fire caused some electrical wires to fall, prompting PG&E to shut off power to the lines.
No one was injured in the blaze, the cause of which remains under investigation, she said.