Hazards at the World Trade Center site included a diesel fuel tank buried seven stories below. Approximately 2,000 automobiles that had been in the parking garage also presented a risk, with each containing, on average, at least five gallons of gasoline. Once recovery workers reached down to the parking garage level, they found some cars that had exploded and burned. The United States Customs Service, which was housed in 6 World Trade Center, had 1.2 million rounds of ammunition and weapons in storage in a third-floor vault, to support their firing range.