It happened Monday just after 2 p.m. at the intersection of Pearl Street and Eades Avenue.
It's believed the 86-year-old driver was leaving the 76 gas station across the street, when her car suddenly accelerated and crashed into the building.
The car also struck a nearby trash can which according to bystanders, sent rocks and other debris flying into the air and struck a pedestrian.
One eye witness said the pedestrian was heard screaming and bleeding as passersby rushed to help him.
San Diego Police and San Diego Fire and Rescue arrived within minutes.
The driver and pedestrian were rushed to nearby hospitals.
The driver's son-in-law arrived at the scene to survey the damage for himself and said he was shocked to hear about the accident.
He described his mother-in-law as very "clear minded" and having a "mind of a 40-year-old."
H also said his mother-in-law suffered a broken ankle and a laceration to the leg.
It's not clear what types of injuries the pedestrian sustained.