of the customers and making sure they're happy. >> outside, a security camera captures a man in a gray hoodie filling his tank. he grabs his cell phone from the front seat to answer a call. eventually, retreats from the chilly night back inside his car to talk on his phone. as two more customers pull in, the man on the cell gets out to remove the nozzle. that's when, without warning this fill-up goes up in flames. >> right at that moment, i turn to my right, and there was like an eight-foot flame shooting out of the vehicle, like you would see a firework on the fourth of july. >> from a truck parked close by off camera, customer mark called 911 in disbelief. >> i called 911 and proceeded to watch this car go up in flames so fast. you start to ask yourself, what's inside the car? >> as the fire accelerates, another danger grows. buried just a few feet below the car, gas reservoirs hold hundreds of gallons of fuel.