A truck bomb exploded Thursday at a security training camp in the western Libyan city of Zliten, killing dozens of people and injuring more than 100 others.

The U.N. special representative to Libya, Martin Kobler, described the bombing as a suicide attack.

It's one of the deadliest attacks in Libya since the 2011 ouster of longtime dictator Moammar Gadhafi. Local and international news reports on the death toll varied, with some saying at least 47 people were killed and others putting the number at 65.

"Hours after the blast, rescue crews at the scene had only managed to extract 60 bodies out of the wreckage, said a hospital spokesman, Moamar Kaddi. Libyan officials said they believed there might be dozens more dead," The Associated Press says.

Two nearby hospitals put out urgent requests for blood donations, Libya's LANA news wire reports.

No group immediately claimed responsibility for the bombing, though AP says that "a local Islamic State affiliate has been trying to gain a foothold in Zliten, spreading westward from its central stronghold of Sirte along the North African country's coast."

NPR's Leila Fadel reports that the explosion occurred amid intensified fighting at two oil terminals hundreds of miles to the east, "as the Islamic State extremist group tries to take control of the area. At least seven oil tanks have been set on fire in the fighting."

Libya slid into chaos after Gadhafi was ousted. The country is divided, with an Islamist militia-backed government based in the country's capital, Tripoli, and an internationally recognized government in eastern Libya. That chaos has benefited local affiliates of the Islamic State group.

Western powers are pressing the two governments to unite. As Leila reports, "In December, there was a U.N.-brokered deal to form a unity government, but it has not been seated and was rejected by many Libyan officials on both sides of the aisle."

And because many stakeholders rejected that deal, some observers worried that it could actually create more chaos.

But in a statement, Libya's U.N. representative says Thursday's attack makes forming a unity government all the more urgent.

"This heinous act once again shows that urgent progress is required toward the formation of the Government of National Accord and the activation and rebuilding of Libyan security forces," Kobler said.

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