Nine people were killed on Monday in clashes between the Libyan army and a militia group in Benghazi.
Gunfire could be heard from 2am onwards and smoke was seen rising in part of the city.
Casualties were reported among both the army and Ansar al-Sharia, a group suspected of killing US Ambassador Christopher Stevens in 2012.
The fighting began after a civilian was stopped at a checkpoint manned by Ansar al-Sharia because he was carrying a weapon.
The army has been driving around Benghazi urging residents to stay at home. An urgent appeal was also broadcast for blood donors.
The BBC reports the government is struggling to contain militias in control of parts of Libya.
Ten days ago, Prime Minister Ali Zeidan called on all militias to leave the capital, Tripoli.