BEIRUT - Lebanese troops and gunmen exchanged fire in Beirut's southern suburbs on Monday, wounding five people, deepening a political crisis following the assassination of a senior intelligence official, security and medical sources said.Four people were also killed, including a 9-year-old girl, and 12 wounded in clashes between gunmen in the northern city of Tripoli, the sources said. The violence heightened fears that the civil war in neighboring Syria could be spreading into Lebanon, upsetting its delicate political balance and threatening to usher in a new era of sectarian bloodshed.Lebanon has been boiling since Friday after Brigadier General Wissam al-Hassan, an intelligence chief opposed to the Syrian leadership, was assassinated in a car bombing.Many politicians have accused Syria of being behind the killing and angry protesters tried to storm the government palace after Hassan's funeral on Sunday.Opposition leaders and their supporters want Prime Minister Najib Mikati to resign, saying he is too close to Syrian President Bashar Assad and his Lebanese ally Hezbollah, which is part of Mikati's government.The clashes in Beirut on Monday morning took place on the edge of Tariq al-Jadida, a Sunni Muslim district that neighbors Shi'ite Muslim suburbs in the south of the capital.Residents had earlier reported heavy overnight gunfire around Tariq al-Jadida between gunmen armed with rifles and rocket-propelled grenades.In Tripoli, a 9-year-old girl shot by a sniper was one of three people killed in overnight clashes. Nine people were wounded, medical and security sources said.The sources said the two dead men were from the Sunni Muslim district of Bab al-Tabbaneh and were killed after gunmen there exchanged rocket and gunfire with the mainly Alawite neighborhood of Jebel Mohsen.In a later incident on Monday morning, a woman was killed and three people wounded by gunfire in the Alawite district. Tripoli has frequently been hit by clashes between Sunnis and Alawites sympathetic to different sides in the Syria war.Thousands of people had turned out in Beirut's downtown Martyrs' Square for Hassan's funeral on Sunday but that ended in violence, with security forces firing tear gas and shots in the air as hundreds tried to storm the prime minister's office.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 Saad al-Hariri said on the Future Television channel on Sunday evening.International envoys call for peaceful resolution of crisisThe crisis in Lebanon underscores local and international concern that the 19-month-old uprising against Assad is dragging in Syria's neighbors.Sunni-led rebels are fighting to overthrow Assad, who is from the Alawite minority that has its roots in Shi'ite Islam. Lebanon's religious communities are divided between those that support Assad and those that back the rebels.Hassan, 47, was a senior intelligence official who had helped uncover a bomb plot that led to the arrest and indictment in August of a pro-Assad former Lebanese minister.A Sunni Muslim, he also led an investigation that implicated Syria and the Shi'ite Hezbollah in the 2005 assassination of Rafik al-Hariri, a former prime minister of Lebanon.Damascus and Hezbollah have condemned Hassan's killing.Mikati said on Saturday he had offered to resign to make way for a government of national unity, but that he had accepted a request by President Michel Suleiman to stay in office to allow time for talks on a way out of the political crisis.Ambassadors from the United States, China, Russia, Britain and France met Suleiman on Monday and appealed to Lebanese leaders to resolve the crisis peacefully.UN Special Coordinator for Lebanon Derek Plumbly, who also attended the talks, said the group condemned "any attempt to destabilize Lebanon through political assassination" and called on all parties in the country to preserve national unity.They expressed support for Suleiman's efforts to start a dialogue among politicians to resolve the crisis.