A United Nations investigation team says a powerful truck bomb caused the explosion that killed former Lebanese Prime Minister Rafik Hariri.

A German prosecutor, Detlev Mehlis, leading the U.N. team told a news conference in Beirut, Friday the blast occurred above ground. Some people believed the explosives were buried under the street, suggesting officials were involved in the plot to kill the former prime minister.

Mr. Hariri and 20 others were killed when his motorcade was blown up on February 14 in downtown Beirut. His assassination was the catalyst for mass anti-Syrian protests and intensified international pressure on Damascus to withdraw its army from Lebanon.

Some information for this report provided by AP and AFP.