"CATASTROPHIC EXPLOSION:" When firefighters arrived at a home in a northern Virginia suburb to investigate a report about a gas smell Friday night, they discovered a 500-gallon underground propane tank with a leak on the side of the residence. Shortly after they arrived, the house exploded and burst into flames, with multiple mayday calls coming from the firefighters trapped inside. Crews rushed in to try to rescue them from the debris that covered them, but one firefighter was killed and 10 oth