Heavy fighting claimed at least six lives and left dozens wounded in Lebanon's capital on Thursday as an escalation of tensions around last year's massive portside explosion turned parts of Beirut into a warzone.
The army deployed tanks and troops to quell the street battles that sparked memories of the 1975-1990 civil war for a city already traumatised by last year's blast disaster and Lebanon's worst-ever economic crisis.
The bloody unrest, in which the sound of automatic gunfire and grenade blasts mixed with the wail of ambulance sirens, broke out after shots were fired at a demonstration by the Muslim Shiite Hezbollah and Amal movements.
The protesters were rallying against judge Tarek Bitar, tasked with investigating the massive ammonium nitrate explosion at Beirut's port that killed more than 200 people and destroyed swathes of the capital on August 4 last year.
The judge had in recent days been in the sights of Hezbollah and Amal in particular for insisting on subpoenaing top officials in his probe.
Thursday's violence started with sniper fire from residential buildings targeting the Hezbollah and Amal supporters, who returned fire with AK-47 assault rifles and rocket-propelled grenades.
"I can't handle these loud sounds, especially the RPGs," said one resident trapped in the combat zone in the city's southern Tayouneh area, who gave his name only as Samer.
"It's the trauma of the Beirut blast coming back all over again."
Interior Minister Bassam Mawlawi said the "exchange started with sniper fire, with the first casualty shot in the head".
He said at least six people were killed, all by gunfire, without specifying who fired the shots.
The Lebanese Red Cross put the number of wounded at 30.
In the chaos, bullets smashed into houses and left craters in the walls of buildings, while many panicked civilians were trapped in their homes. (AFP)