Rival Libyan militias have clashed in the capital, Tripoli, with heavy gunfire and grenade blasts heard in several parts of the city.
At least 10 people are been reported injured. An unconfirmed report says one person has been killed.
One militia is said to be loosely linked to the interior ministry.
It has been blamed for the killing of a rival militia leader from Misrata on Monday and has come under attack in retaliation for his death.
Late on Thursday, pick-up trucks mounted with anti-aircraft guns opened fire as they tried to storm the eastern Suq al-Juma district of Tripoli, witnesses quoted by Reuters news agency said.
“There is no army to protect the simple people, [there are] bullets in the apartments and in the buildings, in our homes,” Tripoli resident Khalid Youssef told the Associated Press.
The attack prompted rival militiamen to fire rocket-propelled grenades.
The Libyan government has been struggling to contain the numerous militias who control many parts of the country.
Some are nominally attached to ministries but often act independently and often have the upper hand over security forces, correspondents say.
Last month, Prime Minister Ali Zeidan was briefly seized by a militia group in Tripoli.
Two years after the overthrow of Col Muammar Gaddafi, Libya still has no constitution and divisions between secular and Islamist forces have paralysed parliament.
BBC
Toka
November 9, 2013 at 2:23 am
Once peace in a nation has been disturbed it is very difficult to restore it. Zambian we need to learn from others. No matter how much we differ on certain issue never should we use fighting as a way of sorting out issues. Gaddafi could have been a dictator but never did what we are seeing happening in libya