The car hit a woman in her 50s and a man in his 40s. Authorities said both were hospitalized in critical condition, though they provided no details about their injuries.
The driver, who was also critically injured, may have lost control due to an undisclosed medical problem, according to a fire department spokesman.
After striking the two people on the sidewalk, the car collided with another car occupied by a man and a woman in their 20s, and a girl about 6 years old. All three were transported to the hospital with non-life-threatening injuries. They were listed in stable condition.
City News Service contributed to this report.