The clashes took place in Tripoli’s city center after one of the capital’s strongest groups assaulted the base of a rival force, witnesses said, leading to hours of shooting that terrified locals and raised fears of a wider escalation.

It was not clear whether the fighting was directly linked to Libya’s wider political standoff over control of the government, but any clashes between powerful Tripoli groups could risk drawing in other factions.

“This is horrible. My family and I could not sleep because of the clashes. The sound was too loud and too frightening,” said Abdulmenam Salem, a central Tripoli resident. “We stayed awake in case we had to leave quickly. It’s a terrible feeling.”

Major armed forces backing each side in Libya’s political dispute have repeatedly mobilized around Tripoli in recent weeks, with large convoys of military vehicles moving around the city and threatening force to obtain their goals.

One man was killed in the shooting, two medical sources and a friend of his told Reuters. Pictures and video shared online of the city center, which Reuters could not immediately verify, showed military vehicles speeding through the streets, fighters shooting and local residents trying to douse fires.

Ali, a 23-year old student who declined to give his surname, said he fled his apartment along with his family during the night after bullets struck their building. “We could not stay any longer and survive,” he added.

There was no immediate comment from the interior and health ministries about the fighting, which paused in the morning before resuming. Tripoli university said it was suspending classes because of the fighting.

The main Libyan standoff pits the Government of National Unity in Tripoli under Abdulhamid al-Dbeibah against a rival administration under Fathi Bashagha, which is backed by the eastern-based parliament.

The United Nations mission in the country warned this week against any attempt to resolve the dispute through violence.

Bashagha tried to enter Tripoli in May, leading to an hours-long shootout that forced him to leave. He has indicated recently that he may try to enter the capital again.

This week factions backing Dbeibah paraded around Tripoli in a show of force, saying they would not allow Bashagha to enter.