They were loading groceries into their car in a parking area in Fairfax County when a man came up and asked if they needed help.
It was in the middle of the afternoon, about 2:45 p.m. Thursday, according to the police, in the 6300 block of Richmond Highway, in what is known as the Alexandria area of the county.
The grocery purchasers went to return their shopping cart. The man who had volunteered his aid got into the car, police said, and drove it away.
He was apparently in a hurry. According to the police, he hit a pole, then drove on through the parking lot and hit a car. The car was pushed into a second car.
The man kept on driving, according to the police account, and reached Richmond Highway. He apparently did not wait around.
Police said officers showed up, but could not find the stolen car.
They said the man who took it was said to be black, in his 30s, slim, and wearing a burgundy jacket, dark trousers and a dark ball cap.