One local official was killed and a militia base reduced to ruins in a clash between rival armed groups near the Libyan capital, the latest flare-up of tension between militias that is destabilising the new Libya.
Two months after Muammar Gaddafi was killed, Libya's new government is still unable to impose its authority on the ground, leaving security in the hands of militias which answer only to themselves and often wage turf wars with their rivals.
The violence in Janzour, a town about 17 km west of the capital, demonstrated that these militias remain the biggest threat to Libya's security despite attempts by the newly-formed interim government to get them under control.
The incident began early on Friday morning, when Ashraf Abdelsalam Al-Marni Swayha, deputy head of the Janzour military council, approached a checkpoint in the town with his driver.
The checkpoint was manned by a militia unit made up largely of fighters from Zintan, a city in the mountains south-west of Tripoli. Zintan fighters played a big role in ousting Gaddafi and have stationed themselves in towns around Tripoli.
According to Abdelnasser Frandah, head of the local council in Janzour, when the fighters at the checkpoint stopped Swayha's car, he told them he was deputy head of the local militia.
They answered him: 'We do not care about the Janzour military council.' He ordered his driver to go and they started shooting at him, Frandah told Reuters on Saturday. He fell as a martyr and the driver was slightly injured.
His account of the incident could not be independently confirmed. The funeral on Saturday of Swayha turned into a show of force by the Janzour militia. About 500 people turned up for the burial, many of them carrying weapons.
As the casket was lowered into the ground, an honour guard of three men in combat fatigues fired into the air from automatic weapons, while other fighters fired a salute from anti-aircraft guns mounted on two pick-up trucks.
Local people said that soon after Swayha's shooting, Janzour residents had gone to the headquarters of the Zintan fighters, a building that used to be an office of Gaddafi's secret police, and ransacked it.
There was no sign of Zintan fighters on Saturday. The burned-out hulks of two jeeps stood outside the former headquarters, and another five vehicles inside the compound had been destroyed. One wrecked car was still hot from the fire.
The attackers had also set fire to mattresses inside the guardhouse. Inside the main building, they had started a fire in one office, leaving the corridor stained black from the smoke.
Frandah said he wanted the Zintan fighters gone for good.
These are revolutionary fighters, we do not want to say anything against them, but the reality is that some of them are outlaws, he said. We are surprised that after liberation (from Gaddafi's rule) we have become captive to these brigades. If we describe it as an occupation we would not be exaggerating.
They fire randomly into the air, they randomly take up positions at government facilities and homes and farms, he said. They must go back to their homes and families and they must take charge of security in their own areas so that what happened here will not happen again.
In a report released last week, the United Nations identified Libya's disparate militias as a major challenge continuing to face the National Transitional Council, the interim leadership which replaced Gaddafi.
There have already been several outbreaks of fighting among the militias. Last month, rival fighters attacked each other with rockets, mortars and machine guns in four days of fighting. They were disputing control of a military base on the main highway between Tripoli and Tunisia.
About a week later, several people were killed in a gunfight after a militia from a district of Tripoli drove into the town of Bani Walid, south-east of the capital, and tried to arrest a local man.
Following those incidents, the transitional council convened tribal leaders at a conference aimed at reconciling rival groups. But the latest violence in Janzour suggests that the conference did not work.
Even at Saturday's burial there was a reminder of Janzour's uncomfortable co-existence with militias from out of town. On a wall near the cemetery, someone had scrawled, in large black letters: Zintan. Land of the brave.