However, there were conflicting reports on the blast in Qubba, located about 30 kilometers from the city of Darna, a stronghold of Libya's branch of the Islamic State group, which has been gaining a foothold in this North African nation, far from the battlefield of Iraq and Syria.
According to army spokesman Mohammed Hegazi, the car bomb exploded next to a gas station in the town as motorists lined up to fill their tanks. The explosion also wounded scores of people, Hegazi told The Associated Press. He added that the gas station is close to the town's security headquarters.
A third attack targeted the security headquarters building itself, said the official, who also gave a different casualty figure, putting the total death toll at around 25.
Such conflicting tolls are common in the aftermath of large attacks. Hospital officials and others in Qubba could not immediately be reached for comment.
Libya has sunk into chaos, four years since longtime dictator Moammar Gadhafi's ouster and death.
The country is split between two rival parliaments and governments. One is based in the capital, Tripoli, and is backed by militias allied with Islamist factions, while the other is the elected parliament, which has been forced to relocate and old sessions in the far eastern city of Tobruk, near the Egyptian border.