Black Saturday (2004)
On May 2, 2004 in a terrorist attack known as Black Saturday, a group of at least four militants in the Saudi Arabian city of Yanbu' al Bahr used security passes to access a local petrochemical plant. Once on the grounds of the facility, they stormed the offices of ABB Lummus and in the ensuing struggle killed six people, of which five were foreign workers and one was a Saudi national guard soldier, and injuring around nineteen others.
Al Qaeda may have been involved in the terrorist attack but Crown Prince Abdullah, de-facto ruler of Saudi Arabia, disputes these claims.