The former Lebanese Finance Minister Mohamad Chatah has been assassinated in a big bomb blast in central Beirut.
He was an adviser to the former Prime Minister Saad Hariri, a Sunni Muslim.
Four others were also killed in the suspected car bombing near government offices and the parliament. At least 50 people were injured.
The Syrian war has increased Lebanon's Sunni-Shia tensions. Lebanon's Shia Hezbollah movement is helping Syria's President Bashar al-Assad.
President Assad comes from the Alawite sect, a heterodox offshoot of Shia Islam.
The Beirut blast damaged several buildings near the Phoenicia Hotel and set several cars ablaze.