The attackers were reported to have smuggled explosives into Saudi Arabia from Lebanon. Al-Mughassil, Al-Houri, Al-Sayegh, Al-Qassab, and the unidentified Lebanese man bought a large latrine service tanker truck in early June 1996 in Saudi Arabia. Over a two-week period they converted it into a truck bomb. The group now had about of plastic explosives, enough to produce a shaped charge that detonated with the force of at least of TNT, according to a later assessment of the Defense Special Weapons Agency. The power of the blast was magnified several ways. The truck itself shaped the charge by directing the blast toward the building. Moreover, the relatively high clearance between the truck and the ground gave it the more lethal characteristics of an air burst.