San Diego Fire-Rescue crews rescued the driver, a 17-year-old girl, from the crash at Relaxx Dry Cleaning in the 1100 block of Morena Boulevard.
What caused the driver to slam into the building around 5 p.m. was not immediately disclosed.
Before crashing into the building, the driver clipped a street sign that lodged into the front of the vehicle and was found inside the dry-cleaning facility.
"The girl tried to go around traffic. Not sure if the gas was stuck or something. She didn't even use the brakes or anything. She was driving about 35 to 50 miles an hour," said Eric Solortano, who witnessed the crash while working next door.
San Diego police investigators have not released results of their investigation and have not said whether the teen driver was distracted or whether the car malfunctioned.
The driver's condition has not been made public, although firefighters at the scene said her injuries did not appear to be life-threatening.