Four fighters were killed in a gun battle between Libyan militias in one of Tripoli's busiest streets on Tuesday, a fresh sign that its new government is struggling to control the increasingly fractious groups that overthrew Muammar Gaddafi.
Former rebels from Tripoli controlling a security compound in the capital fought off dozens of fighters from Misrata who were trying to seize a group of prisoners in a gun battle that lasted for more than an hour, medics and former rebels said.
Real power still resides with the militias, more than two months after they captured and killed Gaddafi. Since then, they have carved up the capital and country into competing fiefdoms, each holding out for the share of power they say they are owed.
After the fighting, armed men combed central Tripoli looking for Misratan fighters. A Reuters witness saw them capture one man, swarm around and kick and punch him as he was marched into the compound.
A pickup truck daubed with the words 'The Defence Brigade, Misrata Revolutionaries' lay across the highway, riddled with bullets and with blood stains on the back seat. One fighter said 11 militiamen from Misrata had been captured.
Some of them screamed 'We're from Misrata, you dogs!' while they were firing, said another Tripoli fighter. They wanted to take them (the prisoners) by force, they used 106mm (rocket) launchers and 14mm machine guns.
The battle on Tripoli's Zawiya road was the first between militias since December 11, when soldiers from Libya's new national army fought militiamen for control of the capital's international airport.
Rival militias with regional allegiances control several compounds abandoned by Gaddafi loyalists as they were overrun in August. Rebels from Misrata in particular hold a vast arsenal of tanks, rockets and guns.
Militias were given a December 20 deadline to leave the capital. They have dismantled most of their checkpoints and limited their presence on Tripoli's streets since then, but have kept some bases, saying they will only hand them over to the state when adequate security forces are in place.
Vehicles carrying dozens of fighters and heavy calibre machine guns blocked roads leading to the compound and snipers were stationed on rooftops.
The situation is under control, said Abdel Hakim Belhadj, an Islamist whose Tripoli Military Council says it has a mandate from Libya's new rulers to secure the capital.
The people who caused the problem were arrested and will face justice, he told reporters.
A few hundred metres down the road at Tripoli's central hospital, dozens of militants filled the corridor leading to the emergency room. A few elderly women, relatives of the dead and injured, sobbed as they hurried towards the hospital.
(Reporting by Mahmoud Habboush; additional reporting by Taha Zargoun; Editing by Ben Harding)