At least 31 people have been killed and nearly 300 wounded after militiamen fired on a demonstration demanding their eviction from Libya's capital Tripoli, the prime minister said.
Hundreds of people carrying white flags in a sign of peace, as well as the national flag, and singing the national anthem had assembled in the capital's Meliana Square.
They then marched to the Misratah militia headquarters in the Gharghour district when gunmen inside fired into the air to scare them off.
But when the crowd continued to move towards the building, the gunmen started firing at them, according to witnesses.
Footage aired on the privately owned al-Nabaa television network showed protesters running from gunfire while carrying others covered in blood.
A Reuters reporter said they saw an anti-aircraft cannon firing from the militia compound into the crowd.
The protesters fled at first but came back heavily armed to storm the gated buildings, where militiamen when were holed up until nightfall.
Dozens of army trucks later arrived to attempt to separate the crowds and militiamen in the compound, sealing off roads to prevent more armed people joining the battle.
Witnesses said some of the militiamen were wounded or arrested, while the remainder eventually fled.
Some of the protesters were armed with weapons too The commander of the militia, Al Taher Basha Agha, vowed in a telephone interview with Libya al-Ahrar accused the protesters of opening fire first.
"Who is the person who is inciting them?" he said. "The evil ones who are using the civilians as a bridge to cross to power.
"Tripoli has not seen a war yet, it will see it soon," he threatened.
Many residents of Tripoli are frustrated with the continued presence of the militia, who are hangovers from the 2011 uprising that ousted dictator Muammar Gaddafi and now a powerful force in the increasingly lawless North African country.
The militia frequently fight with other armed factions in the city.
Prime Minister Ali Zeidan, who was briefly seized by militiamen himself last month, said his embattled government was working on a plan to drive out all militias from Tripoli.
"There will be no exception," he said. "All militias - including those in Tripoli - will be out."
Sadat al Badri, president of Tripoli's city council, which called for the protest, said tensions were rising over the militias.
"We're going to announce a general strike and launch a civil disobedience campaign until these militias leave," he said.
The militias have rejected calls from the weak central government to leave the capital.
The devastated town of Tanuan, south of Tacloba
The Philippines has put the official death toll at 3,633
The PM's visit is the first by a foreign leader to the region since 1948
The crash happened near the Rockefeller Center
The driver claims he was distracted by a cyclist
Miss Green spent four weeks in hospital
People are try to escape the devastation of Tacloban
Julio lost everything when the typhoon hit
Many people have been left with just the clothes on their backs
Many are trying to get to the neighbouring island of Cebu
Helicopters from the USS George Washington deliver supplies
A soldier stands at a checkpoint in the devastated city of Tacloban
Tamils claim they were abused in government-run refugee camps
Sri Lanka's High Commissioner dismissed the claims of torture
Officials are struggling to cope with the sheer scale of the disaster
Body bags are piling up as preparations are made for mass burials
People queue to charge their mobile phones in Tacloban city 
Homes on a hillside in Tacloban have been obliterated by the storm surge
People in the devout Philippines still try to use a badly-flooded church
Typhoon Haiyan has made landfall in southwest China, killing eight people
A woman with an umbrella stands amid the rubble of Tacloban, Leyte
Aerial shots show the true scale of the Typhoon Haiyan destruction
Some families have been forced to take food from damaged shops
Worried relatives have travelled to Leyte to look for loved ones
Human Rights Watch criticises the use of incendiary weapons in Syria
Cars lie abandoned and submerged after Typhoon Haiyan struck
Looters break a shop's butter to make it easier to get food supplies
A woman mourns next to the body of her husband and others
The devastation has left a Hiroshima-like landscape
Emily Ortega lies amid the debris at the airport in Tacloban
A medic places baby Bea on her mother's chest moments after the birth
'Zombie-like' survivors have been left to trudge through thick mud
Oslo: Liu Xiaobo's plight has attracted attention across the world
Government security prevented the Sky crew from talking to his wife
Foreign ministry spokeswoman Hua Chunying 
Residents pick though their belongings after their homes were bulldozed
The Sky team were prevented from filming by site officials
Coastal villages in Leyte were flattened, or swallowed by the storm surge
A child is returned home after leaving an evacuation site in Tacloban
Shivering children wait ito be evacuated from a rescue centre in the city 
A woman about to give birth is carried into a medical centre at Tacloban
Residents beside a road littered with debris
A pregnant woman cooks a meal inside a building overlooking Tacloban
In Vietnam villagers are evacuated in preparation for the arrival of Haiyan
The Natanz uranium enrichment facility