San Francisco’s auto burglary epidemic hit a new and disturbing low over the weekend when someone broke into a man’s car and stole his prosthetic arm, police said Tuesday.

The incident happened around 6 p.m. Saturday on Cleveland Street, an alley in the South of Market neighborhood between Victoria Manalo Draves Park and Seventh Street, near the Hall of Justice.

The crook, who was not identified or arrested, broke into the 41-year-old victim’s vehicle and stole his prosthetic arm, police wrote in a brief report on the incident. Officials initially said a prosthetic leg was stolen but later corrected their report.

The break-in follows a troubling trend of smash-and-grabs, including an incident last month when a couple’s car was burglarized while they took wedding photos at the 16th Avenue mosaic steps in the Sunset District. Days later, a man committed another burglary at the same location while three victims were still sitting inside the vehicle.

The Chronicle last week launched the S.F. Car Break-In Tracker, a tool for readers to see — in near-real-time — the locations of every reported car burglary around the city.

While the crimes continue to plague the city, the number of reported incidents has steadily decreased since hitting an all-time high of 31,067 car break-ins in 2017.

Auto burglaries dropped 17 percent in 2018 and have continued to trend down this year, according to the Police Department’s statistics. The first five weeks of the year have seen a 32 percent drop compared to the same period in 2018, police said.

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky