Flames sparked by an unattended heating tool combined with roofing tar to damage three units of a apartment building in Golden Hill on Saturday evening.
The fire began sometime after 6 p.m. in the building on 30th Street near Grape Street. Crews from San Diego Fire-Rescue extinguished the blaze by 6:56 p.m.
No injuries were reported but six adults were displaced, fire department officials said.
The American Red Cross was called to assist the displaced residents.
City News Service contributed to this article.