A "design flaw" that caused the doors of a Toyota SUV to unlock when the vehicle was placed in park led to the carjacking, kidnapping, and sexual assault of a woman, and to the subsequent hit-and-run murders of a mother and her three children, a lawsuit alleges.

The civil suit, filed against the automaker Wednesday in Philadelphia Common Pleas Court, claims that on July 25, 2014, the woman - a real estate agent whose name is being withheld because she was the victim of a sexual assault - placed her 2005 Toyota 4Runner in park at Cumberland and Cambria Streets while working in North Philadelphia.

The doors automatically unlocked, and Cornelius Crawford, 25, and Jonathan Rosa, 20, jumped into the vehicle, held the woman at gunpoint, and forced her into the back seat as they sped through the streets of Philadelphia and assaulted her sexually, the suit says.

Just 15 minutes into the ride, Crawford crashed the vehicle into a fruit stand at Germantown and Allegheny Avenues, where Keisha Williams, 34, and her three children, ages 15, 10 and 7, were selling produce for a church fund-raiser. All four were killed. Crawford and Rosa fled.

The real estate agent, forced to watch the carnage in horror from her own back seat, got out of the vehicle.

"It was horrible for her," said her attorney, Robert Morris. "She was able to get out of the car and see this poor family."

Morris said that the inexplicable design flaw in the locking mechanisms of the Toyota led directly to the horrific events.

"I can't imagine why a car would be programmed this way at all," he said. "There are no good reasons."

Morris, who is representing the real estate agent and the deceased victims' survivors, filed the suit, alleging negligence, wrongful death, and related claims against Toyota.

The suit also named Crawford as a defendant.

Morris said the surviving victim was never informed by the automaker or the dealer that the doors would unlock when the car was placed in park.

"Do you know what your doors do when you put the car in park?" Morris said. "This isn't something the average consumer thinks about until something terrible happens like this, but it sure should have been obvious to someone designing the car."

A corporate spokesman for Toyota declined to comment on the suit.

Crawford was sentenced this year to 50 to 100 years in prison for his crimes. Rosa is serving 45 to 90 years.