Police and firefighters responded to a blaze in Hayes Valley early Wednesday.
Just before midnight, a shopping cart that may have been next to a garbage can and part of a homeless encampment was set on fire near Oak and Octavia streets.
Several callers to the Fire Department said they thought a homeless person’s belongings were on fire.
A tipster to the neighborhood blog Hoodline tweeted that he was reading in bed when he heard a bang and then saw flames across the street.
Police originally listed the incident as a case of arson but the investigation is ongoing and the Fire Department’s arson unit said they believed it was accidental.
Two cars were damaged in the blaze, Officer Albie Esparza said. One was completely damaged and a second was only scorched by the fire.
A homeless man was interviewed by police, Esparza said, and he told police that he was away from the area collecting materials for recycling and when he returned he saw the fire.
Firefighters extinguished the blaze just after midnight before another truck was called out about 10 minutes later to extinguish a Christmas tree fire nearby in the first block of Haight Street. It is unknown if the two fires were related.