A probable suicide car bombing has killed at least four people at a petrol station in Hermel, a stronghold of the Shi'ite movement Hezbollah.
The Al-Nusra Front in Lebanon, a group named after al-Qaeda's Syrian affiliate, claimed Saturday's attack on Twitter, saying it was a suicide bombing in response to Hezbollah's involvement in Syria.
It was the seventh attack to target Hezbollah in Lebanon since mid-2013, when the group sent men to Syria to fight alongside President Bashar al-Assad's troops against mainly Sunni rebel groups.
"At least four people were killed and more than 15 wounded, two or three of them in critical condition," Interior Minister Marwan Charbel told Hezbollah's Al-Manar television station.
The explosion, which came after nightfall, sparked a huge blaze that hindered the arrival of emergency services.
Al-Manar broadcast footage of a massive fire at the site.
Security forces later closed off the area and firefighters managed to extinguish the blaze.
The petrol station is part of a charitable network set up by Mohammed Hussein Fadlallah, a leading Shi'ite cleric and Hezbollah spiritual guide who died in 2010.
In a statement on Twitter, Al-Nusra in Lebanon said it was a "second martyrdom operation against the Party of Iran (Hezbollah) stronghold in Hermel ... because of the continuation of the Party of Iran's crimes against our oppressed people in our beloved Sham (Syria), and its insistence on sending more of its mercenaries to kill the Syrian people".
"Faced with the massacres it is carrying out, we can only repay the favour in its heartland, to push it to reconsider its calculations."
Caretaker Lebanese prime minister Najib Mikati condemned Saturday's bombing as a "terrorist attack", and called for unity to "protect our homeland".
Syrian Information Minister Omran al-Zohbi, speaking on satellite television channel Al-Mayadeen, said "this terrorist attack, like those before it, only benefits the Israeli enemy".
It was the second blast in less than a month to hit Hermel, in the east of the country and close to the border with war-ravaged Syria.
On January 16, a car bombing outside the main government administration building in Hermel killed three people.
That attack was also claimed by the Al-Nusra Front in Lebanon, a group that has emerged recently.
