At least 27 people were killed and 106 others injured, when clashes broke out between two powerful armed factions in the southern Libyan capital of Tripoli, the country’s emergency services, said in a statement Tuesday.

Fighting began Monday after the detention of the commander of the 444 Brigade, Mahmoud Hamza, as he attempted to travel through Tripoli’s main Mitiga airport.

He was apprehended by a rival faction, the Special Deterrence Force, which controls the airport. The reason for his detention remains unknown.

The clashes ceased late on Tuesday following an agreement reached with the UN-recognized Government of National Unity to transfer Hamza to a neutral party, as reported by state news agency LANA.

Civilians were among the casualties, LANA reported.

The fighting is considered the most severe of this year with images showing smoke rising above the capital following the overnight battles.

The agreement, according to LANA, encompasses the cessation of all military operations in Tripoli, the return of military units to their barracks, assessment of damage to public and private property, and that the Government of National Unity to issue compensations.

The United Nations Support Mission in Libya (UNSMIL) stated on Tuesday that it “is closely monitoring security incidents and developments in Tripoli since yesterday and their impact on the civilian population. The Mission reminds all parties involved of their responsibility under international law to protect civilians.”

The country has seen little peace since it was split between warring factions since 2014, following the 2011 NATO-backed uprising against Moammar Gadhafi.

The Special Deterrence Force and the 444 Brigade are considered the strongest military forces in the Libyan capital, according to Reuters.