The blast happened on Saturday near a petrol station in the northeastern city of Hermel in the Bekaa Valley.
Fire trucks rushed to the Aytam petrol station where flames soared into the night sky.
Residents were urged to keep away from the blast site as paramedics moved in to pull out casualties.
Citing a preliminary investigation, caretaker Interior Minister Marwan Charbel told a local television station that the attack was likely the work of a suicide bomber.
Five people were killed and 20 others injured in a bombing in Hermel on 16 January.
No group has yet claimed responsibility for the Saturday's attack.
However, such attacks have usually been claimed by al-Qaeda-linked groups in Lebanon and Syria.
RA/MB