The fire was reported at about 4:40 p.m. near the intersection of Second Avenue and Balboa Street and was controlled at about 5:15 p.m.
Fire Lt. Ken Smith said the blaze appears to have started in the top floor of a three-story duplex that was under construction at 607 and 609 Second Ave. The fire also damaged two adjacent buildings.
The fire damaged two of four units at 101-107 Balboa St., displacing 15 residents of that building, Smith said. Additionally, a liquor store at the bottom of that building sustained some water damage and will likely be closed for a couple days, he said.
A four-story, single-family home at 611 Second Ave. received some damage, but its residents were allowed to return to the home, Smith said.
There was no report of injuries and the cause of the fire is under investigation. The American Red Cross responded to provide assistance to the displaced residents.