Forces loyal to Libya's National Transitional Council converged on several neighbourhoods in the capital Tripoli on Friday, firing their weapons and confronting what they said were forces still loyal to ousted leader Muammar Gaddafi.
Local residents said a group of a few dozen armed men had earlier appeared in the Abu Salim neighbourhood, a centre of support for Gaddafi, and had begun chanting pro-Gaddafi slogans. Other reports said that men had attempted to raise the green flag of the old regime.
Two Gaddafi supporters and one NTC fighter were killed in the violence, NTC official Abdel Razak al Oraidi said during a press conference in the capital. It was the worst incident in Tripoli since the city fell to the opposition in late August.
NTC fighters in pickups mounted with weapons opened fire at residential buildings, apparently fearing snipers were inside. They also set up checkpoints around the city
About 20 to 50 armed supporters of Gaddafi exchanged automatic and heavy machine gun fire with the NTC forces, one witness told the Reuters news agency.
Al Jazeera's James Bays, reporting from Tripoli, said he could see smoke over the Abu Salim area in the capital.
"The sound of gunfire and heavy weapons being fired also was heard in the neighbourhood," he said.
Assem al-Bashir, a fighter with Tripoli's Eagle Brigade, said the shooting began after a man was spotted raising the green flag that symbolised Gaddafi's ousted regime.
NTC officials said 10 to 15 Gaddafi loyalists were captured.
NTC fighters said fighting had also broken out in the nearby Hadhba neighbourhood.
"Gaddafi told them in a message last night to rise up after Friday prayers," Abdullah, an NTC fighter, said. "That's why these few people have come out and are causing this problem.
Gaddafi has released a number of audio recordings calling on loyalists to fight the new interim government which ousted him from power when its forces captured Tripoli two months ago.
"I urge all Libyan people to go out and march in their millions in all the squares, in all the cities and villages and oases," he said in one such message earlier this month. "Go peacefully ... be courageous, rise up, go to the streets, raise our green flags to the skies."
Fear over loose weapons
As fighting also continued in Sirte, Gaddafi's coastal hometown, where loyalists have withstood an NTC siege for several weeks, the United States said it was growing increasingly concerned over unsecured weapons stockpiles.
The Washington Post newspaper reported on Friday that the State Department had dispatched 14 unarmed civilian contractors to survey and and secure the former regime's ammunition depots. They have so far done so for 20 of 36 such bases.
The United States and other governments are particularly concerned with the spread of surface-to-air missiles, many of them old but still-functioning Soviet-era SA-7s.
Peter Bouckaert, emergencies director for Human Rights Watch, who has been outspoken on the issue, has said there may have been as many as 20,000 surface-to-air missiles in Libya before the revolution and that they have disappeared by the hundreds, trucked off by victorious opposition fighters.
Several missiles have been intercepted by Egyptian officials while being transported from Libya, the Post said.