Gunmen staged overnight attacks on at least six security buildings and outposts throughout Libya’s eastern city of Benghazi, killing six soldiers, military officials said Saturday.

The assaults, which included snipers, rocket-propelled grenades, knife-wielding assailants and explosives thrown onto rooftops, come after a number of smaller targeted attacks and assassinations of security officials in the city over the past several months.

Ali el-Sheikhy, a spokesman for the army’s chief of staff, said no group has asserted responsibility for the attacks. Officials have not announced any arrests.

An elite military unit known as Saaqa said on its Facebook page that Islamic extremists were responsible. It gave no further details.

Security officials say 11 people were wounded, including assailants.

Tensions have been boiling in Benghazi over pro-government militias. Clashes a week ago killed 31 people, mostly demonstrators, during anti-militia protests. The military has since taken over several militia bases in the city, which was the birthplace of the 2011 uprising that toppled longtime dictator Moammar Gaddafi.

The coordinated assault began just after midnight Saturday when hundreds of gunmen in civilian clothes assaulted military outposts and the National Security Directorate with rocket-propelled grenades and heavy weapons. The 1st Infantry Brigade was forced to withdraw from its headquarters when assailants stormed the building. Two army vehicles were destroyed.

Salem Qineydi, the military’s chief of staff, in a statement broadcast on Libyan state TV just before dawn, said a security building was burned down.

A spokesman for Benghazi’s Joint Operations Security Room, Mohammed Hejazi, was quoted by Libya’s official news agency LANA as saying that all six of the soldiers killed were from an elite military unit known as Saaqa. He said four died from gunshots to the head from snipers and two were “slaughtered by knives,” but gave no other details.

Saaqa confirmed the six killed were from its ranks. On its Facebook page, it blamed Islamic extremists for the attacks.

The fighting lasted until late morning after spreading to areas around Benghazi’s international airport, which officials closed Saturday as a precaution. Reinforcements have been sent from the capital, Tripoli, to Benghazi, the country’s second-largest city.

A security official in Benghazi, who spoke on the condition of anonymity out of concern for his safety, said fighting also occurred in residential areas.

— Associated Press