A truck bomb detonated at a military training center in a western town in Libya has killed dozens and wounded many more, according to reports.
Witnesses said on Thursday the vehicle crashed into the gate of the academy in the coastal city of Zliten, around 100 miles east of the capital Tripoli.
A hospital source told Reuters that at least 65 people were dead following the attack.
Libyan local news agency LANA put the death toll at more than 50.
There was no immediate claim of responsibility for the attack.
Libya has been beset by chaos since the 2011 overthrow of longtime dictator Muammar Gaddafi and groups affiliated to the Islamic State of Iraq and the Levant (ISIL) have been gaining increasing influence.
The U.N. envoy to Libya, Martin Kobler, said on Twitter that the blast was a suicide attack.
"I condemn in the strongest terms today's deadly suicide attack in Zliten, call on all Libyans to urgently unite in fight against terrorism," he wrote.
Libya has had rival administrations since August 2014, when a militia alliance overran Tripoli, forcing the government to take refuge in the east.
The United Nations is pressing both sides to accept a power-sharing deal.
On December 17, under U.N. guidance, envoys from both sides and a number of independent political figures signed a deal for a unity government, but the agreement has yet to be implemented.
World powers fear Libya could descend further into chaos and become a stronghold of IS on Europe's doorstep.
The group claimed a string of atrocities in Libya last year, including the January attack on a luxury hotel in Tripoli known for hosting foreign diplomats and Libyan officials, which killed nine people.
A month later it released a video showing the beheading of 21 Coptic Christians, all but one of them Egyptians, that armed men said they captured in Libya in January.
In a report to the U.N. Security Council in November, International Criminal Court chief prosecutor Fatou Bensouda said that ISIL had been responsible for at least 27 car and suicide bombings in Libya in 2015.
ISIL has in recent days launched a series of attacks on oil facilities in eastern Libya, pushing east from the group's coastal stronghold of Sirte.
Officials have warned of crippling consequences for the country if the group manages to seize control of Libya's oil resources.
Oil is Libya's main natural resource, and the country sits on reserves estimated at 48 billion barrels, the largest in Africa.
Al Jazeera and wire services