Several armed men attacked the headquarters of Libya’s National Oil Corporation (NOC) in the capital Tripoli on Monday, killing at least two oil staff, a security official said.

In the first attack of its kind against the top managers of Libya’s state oil industry, two of the gunmen were also killed and at least 10 NOC staff wounded, officials said.

Security forces said they had regained control of the landmark glass-fronted building in the center of the city.

The Interior Ministry in Libya's Government of National Accord and Tripoli's 'Deterence Force' blamed ISIS for the attack. According to the Interior Ministry the attack was carried out by six ISIS members.

The attack came less than a week after a fragile truce halted fierce clashes between rival armed groups in Tripoli.

The NOC provides the income for Libya and, along with the Tripoli-based central bank, is only state institution still functioning well amid chaos.

No group immediately claimed responsibility for Monday’s attack. Militants loyal to Islamic State have previously carried out attacks in Tripoli and other Libyan towns and cities.

Gunfire rang out in the morning as security forces allied to the Tripoli-based government arrived.

“The death toll so far is two killed from NOC staff and two attackers,” said Ahmad Ben Salim, spokesman for the Special Deterrence Force (Rada), one of the most powerful factions in Tripoli.

Security forces smashed windows so staff could escape and several people were hurt by shattered glass, witnesses said. NOC Chairman Mustafa Sanalla and his office manager were seen safely leaving the building.