Two Libyan militia factions clashed in a gun battle on one of Tripoli's busiest streets on Tuesday, leaving four fighters dead and at least five injured.
A militia group from the city of Misrata confronted a group of former rebels in Tripoli as they tried to free prisoners held inside the old intelligence building from Libya's ancien regime.
Colonel Walid Shouaib, a member of Tripoli Military Council, said the fatal skirmish was sparked by the arrest of a Misrata fighter on New Year's Eve by Tripoli fighters.
Since Colonel Gaddafi's regime was finally toppled in October, security has been a threat in the country as disperate militias wrestle for power, the BBC's correspondent on the ground explained.
The battle was the first between militias since December, when soldiers from Libya’s new army fought militias for control of the capital’s international airport.