A car bomb struck a stronghold of the Shia armed group Hezbollah in eastern Lebanon, injuring both civilians and members, Lebanon's state-run news agency said.
The National News Agency (NNA) reported that Tuesday’s blast near the remote village of Sbouba in the Baalbek region "was caused by a suicide bomber".
Beirut-based The Daily Star daily said the suicide bomber drove an explosives-laden vehicle into two vans carrying Hezbollah members.
Hezbollah's Al-Manar TV confirmed the blast, adding that the attack took place near a Hezbollah transit point hub.
There was no immediate word on the nature of the explosion or the target.
Al Jazeera's correspondent in Lebanon said 10 were injured in the attack.
The explosion appears to be part of a wave of attacks on Hezbollah strongholds and interests in Lebanon. The group is fighting in Syria alongside President Bashar Assad's troops and has received threats of retaliation from the largely Sunni rebels fighting to topple him.
NNA said the car bomb was "intercepted" at a Hezbollah checkpoint and exploded after members of the checkpoint fired on it, the report said. It was unclear if the car detonated from the gunshots or if the driver set off the explosion.
Ambulances were rushing to the area, which was sealed off by the armed group, the agency reported.
Hezbollah's participation in the conflict in Syria is highly divisive in Lebanon, where many feel it has deviated from its original purpose of fighting Israel and that it has exposed the Shia community to retaliation.
The group's open support of the Assad regime has enraged Sunnis and left it with no shortage of enemies eager to strike at its strongholds and leadership.
Dozens of people have been killed in deadly car bombings claimed by Sunni armed groups.
Most recently, on December 4, gunmen assassinated a senior Hezbollah commander, Hassan al-Laqees, in the garage of his building in a Hezbollah stronghold in southern Beirut.
Last month, two suicide bombers blew themselves up outside the Iranian Embassy in Beirut, killing 23 people. An al-Qaeda-affiliated group claimed responsibility, saying it was payback for Hezbollah's support of Assad.