Muni spokesman Paul Rose said the 43-Masonic bus hit a car making an illegal U-turn near the intersection of Fell Street and Masonic Avenue at about 6:20 p.m.
Pictures posted to social media showed the bus well inside the park with the car crumpled in front of it.
The bus driver was transported to San Francisco General Hospital and the car's driver refused medical aid, Rose said. No one else was injured.
