Petaluma fire Battalion Chief Jeff Holden said a man was behind the wheel of a Honda Accord was in the parking lot of the Westamerica Bank at 203 S. McDowell Blvd. at about 6 p.m. when something went wrong and he hit the gas pedal.
The car accelerated through the parking lot, drove over a curb and some shrubbery and went straight across South McDowell Boulevard, Holden said.
It didn't hit any other cars and continued across the street, jumping a curb and crashing through a chain-link fence before smashing through the front door and window of 228 S. McDowell Blvd.
A mother and her daughter, who appeared to be 11 or 12 years old, were relaxing at home, with the girl sitting at a table and the woman on the couch, Holden said.
"The girl was sitting at the kitchen table when the car came into the residence and came within a couple of feet of hitting her," he said. "It knocked the chair she was sitting in over."
When the car came to rest, it was almost entirely inside the one-story home, Holden said.
The mom and the daughter were both OK, and the driver, a man Holden estimated to be in his late 50s or early 60s, was able to get out of the car on his own.
He was taken to Petaluma Valley Hospital to be evaluated.
Witnesses reported that the man appeared to be asleep or unconscious as the car crossed South McDowell Boulevard, Holden said.
Holden said firefighters were amazed the Honda, which was traveling at an estimated 30 mph, didn't hit any other cars.
"One of the guys referred to it as 'Frogger' because it's very busy right there at McDowell at Washington at 6 o'clock at night," he said.
A while after the crash, the husband and a brother arrived home and saw the damage for themselves, Holden said.
"He said, 'My wife called and told me there was a car in our house, and there is a car in our house,'" Holden said. "He thought she might have been exaggerating."
The family has been displaced, he said.