SAN FRANCISCO (CBS SF) — Firefighters have contained a two-alarm residential structure fire in San Francisco’s Nob Hill neighborhood Tuesday afternoon.

The fire was reported at 3:47 p.m. in the 1400 block of Taylor Street, near Pacific Avenue.

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Crews arriving at the scene found heavy fire affecting two different three-story structures with a total of 20 residential units between them.

The fire was under control by 4:33 p.m. The cause of the fire has been deemed accidental in nature, although further information was not immediately available.

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It’s not yet clear how many, if any, residents were displaced.