The crash happened around 4:30 p.m. at 3rd and Mission streets.
Police say a third pedestrian who was hit was taken to the hospital and his condition is unknown at this time.
The taxi cab driver was taken to the hospital and is in stable condition.
SFPD PIO Officer Robert Rueca says, "Officers responded to the scene and located pedestrians who were struck by a vehicle that drove onto the sidewalk."
Police say the taxi and a car were both entering the intersection when the accident occurred, revealing few other details.
If you're on the ABC7 News app, click here to watch live
Ofc. Rueca says, "This vehicle was involved in a vehicle collision with another vehicle that remained on scene."
The scene drew a lot of attention, blocking off traffic for several hours for police to investigate.
ABC7 News also spoke with several nearby residents, who say they are seeing more and more accidents in the area.
District 6 Supervisor Matt Dorsey echoed their words. "This is a neighborhood that is disproportionately affected by traffic accidents and, sadly, this one that happened and our hearts go out - there were two fatalities here today."
Ofc. Rueca says, "MTA's worked very hard at trying to make these roadways as safe for those... be it vehicles, cyclists and pedestrians."
Police say, at this time, they don't believe alcohol or drugs played a role in this accident, nor do they suspect road rage. They add it will take time to figure out exactly what happened here.
Anyone with information is asked to contact the SFPD at 415-575-4444 or text a tip to TIP411 and start the message with SFPD.