A strong explosion shook downtown Beirut on Monday in a commercial area where popular hotels are located, killing at least six people, according to witnesses. Television footage showed one person ablaze falling out of a burning car's window. The Associated Press quoted Witnesses and a politician as saying that the explosion was apparently targeting former Prime Minister Rafik Hariri, whose motorcade passed the area shortly beforehand. TV footage from the scene showed the devastated front of a building and flames leaping from several cars. A burning person struggled to get out of a car via the window, fell on the ground and was helped by a bystander who used his jacket to put out the flames. The blast severely damaged at least one large building, the facade of which was blown off, covering cars, sidewalks and the street with rubble. Heavily armed security forces cordoned off the area with yellow tape as rescue workers and investigators combed the scene apparently looking for casualties or clues to what caused the huge explosion. The explosion near the city's waterfront shortly before noon (1000GMT) shook buildings in the city center and was heard in outlying hills overlooking the Lebanese capital. Rubble and twisted debris covered a road lined with burning cars, the smoke from which enveloping the area as firefighters carrying houses raced to douse flames. A man and a woman were seen walking in separate locations with blood running down their faces. The cause of the explosion was not immediately known.