SAN FRANCISCo (CBS SF) — A Wednesday night fire heavily damaged a vacant San Francisco home and then spread to a neighboring home in the Mission District before it was brought under control, authorities said.

San Francisco Fire PIO Jonathan Baxter said the first call came in at 6:31 p.m. reporting the blaze in a two-story vacant residential building at 1007 Shotwell Ave.

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Arriving firefighters discovered the fire had spread to the residential building next door and called in a second alarm.

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The blaze was brought under control in less than an hour but not before it had displaced 11 people.

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There were no injuries and the fire remained under investigation.