Two bombs have exploded minutes apart near the Lebanese capital, killing three people and wounding 20 others.
Several other vehicles were badly damaged by the blasts
The casualties were travelling on two buses near Bikfaya, a mainly Christian town in the hills north of Beirut.
Initial reports said 12 people had died. Investigators sealed off the area to collect evidence from the wrecks.
The bombings come at a time of acute political tension in Lebanon, and a day before the second anniversary of the killing of former PM Rafik Hariri.
Organisers of a mass rally planned in downtown Beirut on Wednesday to mark the Hariri assassination said there were no plans to cancel it.
Lebanese radio said the buses were passing through the village of Ain Alaq, just south of Bikfaya.
The BBC's Jim Muir in Beirut says this clearly well-planned attack, involving considerable organisation, will reinforce fears of many Lebanese that hidden hands are at work trying to stir up civil strife.
Officials said the first bus exploded, causing damage and casualties, and as people rushed to the scene, a second explosion ripped through the second bus as it drove up behind it.
The death toll was initially reported as much higher, but the Lebanese Red Cross said its workers had only delivered three bodies to hospitals.
Bikfaya is the ancestral home of the Gemayels, one of the most prominent Christian families in Lebanese politics.
Pierre Gemayel, a member of Lebanon's western-backed, anti-Syrian coalition government, was gunned down by unknown attackers in East Beirut last November.
Three other prominent public figures from the anti-Syrian camp have died in bombings in the last two years. Syria has always denied accusations of involvement.
Saad Hariri, Rafik's son and political heir, described the bombings as a "cowardly terrorist attack" designed to disrupt the anniversary ceremonies.
President Emile Lahoud, of the pro-Syrian camp, said they were a clear attempt to foil a peaceful resolution between Lebanese factions.
"Every time the possibility of practical solutions looms on the horizon between the Lebanese factions to strengthen their unity, the enemies of Lebanon rush to commit a new crime against innocents," he said in a statement.
Political and sectarian tensions have running high in Lebanon, erupting in clashes in January between supporters and opponents of the government.
Correspondents say organisers from the different political factions have been working hard to avoid problems at Wednesday's pro-government rally, close to where opposition supporters have been holding a sit-in.
Lebanon's political crisis arose when six pro-Syrian ministers resigned in November, primarily over the endorsement by the cabinet of a UN tribunal to try suspects in the Hariri bombing.