A bomb exploded near a bus carrying civilians and members of the military in the northern city of Tripoli early on Wednesday, killing at least six people and wounding others, security officials said.
The officials said the bomb was planted on the side of a road and went off when the bus passed by, causing the casualties. They said the explosion happened as the streets were filled with people heading to work, which contributed to the many injuries. Television footage showed a small public bus riddled with shrapnel from the blast. Shattered glass could be seen in the Banks Street in Tripoli's center.
The officials spoke on condition of anonymity because they were not authorized to speak to the media.
Tripoli has witnessed sectarian clashes in the past weeks that killed and wounded dozens of people.
The city is also close to the Palestinian refugee camp of Nahr el-Bared, which experienced deadly clashes last year between Lebanese troops and members of the al-Qaida -inspired Fatah Islam group.
The latest violence comes at an especially sensitive time for Lebanon.
On Tuesday, after a five-day debate and weeks of negotiations that preceded it, the parliament approved a national unity government that gives the Iranian-backed Hezbollah opposition a more powerful say in the running of the country, including veto power over major decisions.
The explosion also comes as Lebanese President Michel Suleiman is expected on a landmark visit in neighboring Syria _ the first visit by a Lebanese president in about three years.