4/5/2023 954PM-Neville Island bridge, Pittsburgh, PA While traveling on the interstate, the vehicle caught fire with no warning. We were heading out on vacation, so we had lots of things packed in the car. The fire started in the rear of the vehicle, and was extinguished by a passer by with a fire extinguisher, but re-ignited. it burned VERY fast. Unknown at this time what caused the fire. It is currently in the hands of my car insurance company, so it may be available for inspection. There were NO indications of a problem prior to large flames erupting form the read of the vehicle. In the car was myself, my two adult daughters and 6 year old grandson. He was seated in the 3rd row seat. One daughter in the second row, and myself and daughter up front. Once we realized we were on fire, we attempted to get the back doors open, but child locks were engaged. The key fob would NOT work, and my daughter and grandson were trapped in the burning car. we attempted to break the windows to get them out, but that was not successful. My daughter climbed back in the burning car and somehow got a back door open and they were able to get out and run. Within a few seconds, the windows blew and the flames shot even higher. We will NEVER EVER use child locks again. The problem had not been confirmed or reproduced to my knowledge. I believe my insurance company may be looking into it. I had to have a fuel system regulator and sensor replaced on this vehicle approx 1 month before this