Gunshots were heard in Libya's capital amid clashes between two armed groups aligned with the U.N.-backed unity government.
Several residents in Tripoli were lightly wounded in the clashes, which began Sunday night and spread across several neighborhoods.
Fighters from rival militias – the Al-Raada Force and the 444 Brigade, both loyal to interim Prime Minister Abdul Hamid Dbeibah's Tripoli-based government – clashed after a member of the 444 Brigade was arrested.
Libyan television and online media showed videos of the fighting posted online by social media users.
An elderly man "was injured in the arm by shrapnel as he fled his home in Ain Zara by car," the Tripoli Rescue Service said on its Facebook page, condemning damage to ambulances during the gun battles.
On Sunday, armored vehicles and fighters were seen deploying in Jrabra Street, a busy commercial area in the capital's east, and the central Ras Hassan residential district.
After a lull in the fighting, heavy and light weapons fire was heard, along with ambulance sirens, in the eastern suburbs of Ain Zara and Fornaj until 3 a.m. (01:00 GMT) Monday, according to an Agence France-Presse (AFP) correspondent.
The University of Tripoli said Monday it was forced to "close its doors" and suspend exams as a security measure.
The fighting was reportedly halted after the intervention of another armed group responsible for security, the Stabilisation Support Agency.
Libya is split between Dbeibah's United Nations-backed government in the west and another in the east backed by putschist Gen. Khalifa Haftar.
The oil-rich country was plunged into chaos after a NATO-backed uprising toppled and killed Moammar Gadhafi in 2011.
Last August, 32 people were killed and 159 wounded in Tripoli when groups supporting the Haftar-backed government fought with Dbeibah's forces.
The latest Tripoli fighting comes after Dbeibah's government carried out drone strikes since Thursday near the western city of Zawiya, claimed to be on targets connected to fuel and drug smuggling and people trafficking.
On Sunday, drone strikes killed at least two people and hospitalized the nephew of legislator Ali Bouzribah, from the rival eastern parliament, whose home had reportedly been hit in strikes three days earlier.
The eastern-based Parliament on Monday denounced the strikes against Zawiya, saying it was an operation to "settle political scores rather than fight against traffickers as claimed" by the Dbeibah government.
In response, the U.S. embassy in Tripoli said it was monitoring the situation with "concern amid reports of weapons being used in civilian areas and the potential for further violence."
"Libyan leaders should do everything they can to de-escalate and take every precaution to protect the lives of civilians," it tweeted.
Britain branded it as "unacceptable" to use weapons that put civilian lives at risk and called on all those involved to de-escalate, its embassy said on Twitter.
