While driving in highway we noticed a fuel smell. After a little came from front area (hood area) and heard a blast underneath. At the same time the car abruptly stopped in the highway (HOV lane). We also noticed fireballs shooting downward from underneath the car. We had no options but to call fire brigade to stop the fire. Later we had to tow the car to home. I called a mechanic to evaluate the situation and he informed us the engine of the vehicle has been ceased as a result. We have to bear a significant cost for the repairs. We are still suffering emotional stress as a result of this unexpected incident.