At least 65 people were killed when a truck bomb hit a police training centre in the Libyan town of Zliten on Thursday, a hospital source said.
Dozens more were injured in the attack, which happened as hundreds of recruits were gathering for a graduation ceremony.
Mayor Miftah Hamadi said the bomb detonated as recruits were gathering at the police centre in Zliten, a coastal town between the capital Tripoli and the port of Misrata.
BBC reported that, the UN Special Representative to Libya, Martin Kobler, said that the blast was due to a suicide attack. It added that ISIS militants are gaining foothold in Libya after the overthrow of ousted Libyan leader Muammar Gaddafi in 2011.
Since the NATO-backed revolt ousted Gaddafi, Libya has slipped deeper into turmoil with two rival governments and a range of armed factions locked in a struggle for control of the North African state and its oil wealth.
In the chaos, Islamic State militants have grown in strength, taking over the city of Sirte and launching attacks on oilfields. Islamic State fighters this week attacked two major oil export terminals.
In February last year, three car bombs hit the eastern Libyan city of Qubbah, killing 40 people in what officials described as a revenge attack for Egyptian air strikes on Islamist militant targets.
(At The Quint, we question everything. Play an active role in shaping our journalism by becoming a member today.)