A sinkhole appeared near a roadwork site Thursday evening in Pacific Heights, according to the San Francisco Public Utilities Commission.
A 17-foot by 22-foot area of Sacramento Street collapsed between Lyon and Baker streets around 5 p.m.
Road crews were already nearby, filling in an indentation in the street, when the collapse occurred. No injuries were reported.
The incident appears to have been caused by a sewer main break at the same location, although the cause of the break is not yet known. Water and sewer service has not been affected, however.
Crews have secured the scene, and Sacramento Street is closed between Lyon and Baker. Muni lines have not been affected.
Repairs, which will begin Friday morning, are expected to take two to three days to complete.