Malek Merset, the spokesperson for Libya's Emergency Medicine and Support Center, said Wednesday that the death toll had risen from 27 to 45, as more casualties were confirmed. An additional 146 were injured, up from 106 on Tuesday. It remains unclear how many of the dead were militiamen or civilians.
The clashes between the influential 444 Brigade and the Al-Radaa, or Special Deterrence Force, two of the myriad of militias that have vied for power since the overthrow of longtime dictator Moamer Kadhafi in 2011, erupted on Monday night and raged through Tuesday.
A total of 234 families were evacuated from frontline areas in the capital's southern suburbs, along with dozens of doctors and paramedics who had got trapped by the fighting while caring for the wounded, the center said.
Three field hospitals and a fleet of around 60 ambulances had been deployed to the area when the fighting broke out.
The clashes were triggered by the detention of the head of the 444 Brigade, Colonel Mahmud Hamza, by the rival Al-Radaa Force on Monday, an interior ministry official said.
Late Tuesday, the social council in the southeastern suburb of Soug el-Joumaa, a stronghold of the Al-Radaa force, announced an agreement had been reached with Prime Minister Abdelhamid Dbeibah, head of the U.N.-recognized government based in the capital, for Hamza to be handed over to a "neutral party."
In a televised announcement, the council said a ceasefire would follow the transfer of the force's commander and late Tuesday the fighting abated.
Both armed groups are aligned with Dbeibah's government, one of two rival administrations that vie for power through shifting alliances with the militias on the ground.
Overnight, Dbeibah visited the southeastern suburb of Ain Zara, which saw some of the heaviest fighting on Tuesday, accompanied by Interior Minister Imed Trabelsi.
Dbeibah "saw for himself the severity of the damage" as he toured the densely populated neighborhood's unlit streets, his government's press office said on its Facebook page.
He gave instructions for a survey of the damage to be carried out so that residents could be compensated, it added.
The interior ministry put in place a security plan to deploy officers to battleground districts to oversee the truce announced between the two sides.
The Libyan capital's only civilian airport, Mitiga, which lies in an area under Al-Radaa's control, remained closed to commercial flights on Wednesday, officials said. Flights were being diverted to Misrata about 180 kilometers (110 miles) to the east.
Libya has seen more than a decade of stop-start conflict since the NATO-backed revolt that toppled Kadhafi.
In May, the two armed groups had clashed for hours in Tripoli, also after the arrest of a 444 Brigade member.
A period of relative stability had led the United Nations to express hope for delayed elections to take place this year, and the latest fighting triggered international calls for calm.
The United Nations Support Mission in Libya said it was "following with concern" the security deterioration in the Libyan capital and its impact on civilians.
"All parties must preserve the security gains achieved in recent years and address differences through dialogue," UNSMIL said.
The embassies of Britain, France, the European Union and the United States, echoed the U.N. call for de-escalation.
The 444 Brigade is affiliated with Libya's defense ministry and is reputed to be the North African country's most disciplined. It controls the southern suburbs of Tripoli, and other areas.
The Al-Radaa Force, commanded by Abdel Rauf Karah, is a powerful ultra-conservative militia that acts as Tripoli's police force.
It positions itself as independent of the interior and defence ministries, and controls central and eastern Tripoli, Mitiga air base, the civilian airport and a prison.
Libya is split between Dbeibah's U.N.-backed government in the west and another in the east backed by military strongman Khalifa Haftar.
In August last year, 32 people were killed and 159 wounded in Tripoli when groups supporting the Haftar-backed government fought with Dbeibah's forces.
Elections in Libya had been due in December 2021 but disputes including who could stand in the polls resulted in their suspension indefinitely, although the U.N. has been working to end sticking points.
Information for this report came from The Associated Press and AFP.