The accident was first reported at about 9:30 in the city's Visitacion Valley neighborhood at San Bruno and Arleta Avenues.
Investigators said the car shutdown and the driver had no control as she slammed into a group of people waiting for a bus. Because of the heat, the pedestrians were waiting in the shade of an apartment building and not a bus shelter.
"Her vehicle lost power, she lost the ability to brake, to steer the vehicle and as the vehicle was coming down the hill it gained speed and it veered across the street into a group of people that were waiting for a bus at this bus stop. We have five injuries as a result of this accident. Four people were transported with life threatening injuries. One person was transported with non-life threatening injuries," said Mindy Talmage of the S.F. Fire Department.
The driver is quite distraught and very upset about what happened.
Buses have been rerouted until the accident is cleared.