Several people have been killed and dozens of others wounded when gunfire erupted during a protest in Beirut by the armed group Hezbollah and its allies against the lead judge investigating last year’s massive explosion at the city’s port.

At least six people were killed and 25 others wounded in the gunfire, the Lebanese Red Cross told Global News Insight.

The exchanges of fire involving snipers, pistols, automatic rifles, and rocket-propelled grenades were a dangerous escalation of tensions over the domestic probe.

Gunfire echoed in the capital and ambulances rushed to the scene, sirens wailing. Snipers shot from buildings. Bullets penetrated apartment windows in the area. Four projectiles fell near a private French school, Freres of Furn el Chebbak, causing panic, a security official said, speaking on condition of anonymity because he was not authorized to speak to the press.

The students huddled in the central corridors with the windows open to avoid major effect, in scenes reminiscent of the 1975-90 civil war.

The protest outside the Justice Palace was called for by the powerful Hezbollah group and its allies who are demanding the removal of Judge Tarek Bitar.

It was not immediately clear what triggered the gunfire, but tensions were high along a former civil war front line between Shia and Christian areas.

In a statement, Prime Minister Najib Mikati appealed for calm and urged people “not to be dragged into civil strife”.