Lebanese troops launched a major security operation to open all roads and force gunmen off the streets, trying to contain an outburst of violence set off by the assassination of a top intelligence official who was a powerful opponent of Syria. Sectarian clashes killed at least six people. Gunfights have broken out in several areas of Lebanon following Sunday's funeral of anti-Syrian intelligence official Wissam al-Hassan, raising fears that his assassination will further destabilise the country. On Monday, clashes between Lebanese troops and unidentified armed men took place in Beirut, the capital. Several people were wounded after the army made a pre-dawn sweep through the district of Tariq Jdideh in pursuit of armed men, and automatic weapons and anti-tank rocket fire could be heard. The worst of the clashes since late Sunday took place in the northern city of Tripoli, the scene of previous fighting between Sunni Muslims backing the Syrian opopsition fighter and Alawites sympathetic to Syrian President Bashar al-Assad. The two sides exchanged rocket and gunfire, residents said. Among the victims were a nine-year-old girl shot by a sniper. Opposition leaders have urged their supporters to refrain from any more violence. "We want peace, the government should fall, but we want that in a peaceful way. I call on all those who are in the streets to pull back," former prime minister and opposition leader Saad al-Hariri said on the Future Television channel on Sunday evening from Saudi Arabia, where he has been living for over a year.