At least 40 people are believed to have died in suicide attacks carried out by the Islamic State of Iraq and the Levant group in eastern Libya, apparently in retaliation for Egyptian air strikes against ISIL's new branch in North Africa.
Friday's bombings in the town of Quba, which is controlled by the paramilitary force of former General Khalifa Haftar, added to concerns that ISIL has spread beyond the battlefields of Iraq and Syria and established a foothold in North Africa.
ISIL claimed responsibility for the suicide bombings in Quba, about 250km east of Benghazi, but said there were only two attacks, while the government said there were three.
ISIL released a video on Sunday that showed the beheading of 21 Egyptian Christians who were abducted in Sirte, and Egypt responded on Monday with air strikes on Derna, a city about 30km from Quba.
The coastal Mediterranean cities of Sirte and Derna are under ISIL's control at present.
Mohammed Hegazi, an army spokesperson, said one attacker drove an explosives-packed ambulance into a petrol station where motorists were lined up.
"Imagine a car packed with a large amount of explosives striking a petrol station; the explosion was huge and many of the injured are in very bad shape while the victims' bodies were torn into pieces," Hegazi said.
Two other bombers detonated vehicles next to the house of the parliament speaker and the nearby security headquarters, Hegazi said.
Two rival governments
Libya is split between two rival governments.
The elected and internationally recognised government has been forced to relocate to the eastern city of Tobruk near the Egyptian border because Tripoli has been overrun by the Islamist and tribal groups.
Meanwhile, an older pre-election parliament, supported by the armed groups, has remained in Tripoli and declared itself legitimate.
Mohammed Bazaza, spokesperson for the internationally recognised government, put the death toll at 40, with at least 70 injured, some seriously.
The number of dead was expected to rise.
Two security officials, speaking on condition of anonymity because they were not authorised to talk to the media said at least 45 were killed.
Among the dead were at least five Egyptians working at a cafe next to the petrol station.
Video broadcast from the scene showed dozens of cars wrecked and ablaze, with pools of blood on the asphalt, along with body parts, shoes and shattered glass.
Bodies covered in sheets were lined up nearby. The government announced a week of mourning.
"This terrorist, cowardly and desperate attack only increases our determination to uproot terrorism in Libya and in the region," Bazaza said, adding that Libyan air force jets conducted several air strikes, without specifying where.
Witnesses in the city of Sirte said it was hit by multiple Libyan air strikes on Friday, targeting a convention centre that is used by ISIL as its headquarters.
Jen Psaki, US State Department spokesperson, said the administration condemned the attacks in Quba.
ISIL has established its presence in Libya by exploiting the country's breakdown since long-time ruler Muammar Gaddafi was toppled and killed in 2011.
Hundreds of armed groups have taken power since then, and some of them have al-Qaeda-aligned ideologies.
A militia coalition known as Libya Dawn has taken over Tripoli, where Islamists set up their own government.
A like-minded group controlled the eastern city of Benghazi until late last year, when government forces began battling them for control.
In addition to launching air strikes on Derna earlier this week, Egypt joined Libya's elected government in pressing for a UN Security Council resolution to lift a UN arms embargo on Libya and pave the way for international intervention - similar to the US-led campaign in Syria and Iraq against ISIL.
But Security Council members US and Britain rejected the call, saying on Thursday that Libya needs a national unity government first.
Bazaza repeated an appeal for lifting the arms embargo.
The Tripoli-based government, which is partially supported by Islamist factions and armed groups from the western city of Misrata, continue to deny the presence of an ISIL affiliate in Libya.
Source: Al Jazeera and agencies