While sitting stopped at a red light, the brake pedal suddenly became soft and the vehicle began moving. As I rushed to depress the pedal further (all the way to the floorboard - which did not stop the car) the car rolled forward and collided with the car in front of us causing damage to both vehicles. If the other car had not been in front of us we would have rolled directly into heavy active cross traffic which would have caused significant harm to all inside. My daughter, niece, and 8 month old grand-niece were with me in the car.