Gunfire killed two people and wounded 12 at a Beirut rally organised by the Shiite Hezbollah and Amal movements Thursday to demand the dismissal of the Beirut blast lead investigator, a doctor said.
One man died of a gun shot to the head and the other of a shot to the chest, said Mariam Hassan of the Sahel Hospital in Beirut's mainly Shiite southern suburbs.
Twelve wounded are in critical condition, the doctor said, reporting a continued influx of casualties.
AFP correspondents in the area heard heavy gunfire.
Lebanese television broadcast images of men carrying rifles and heavy weaponry.
In a follow-up statement, the military warned that it would open fire at anyone firing live rounds, calling on civilians to evacuate the area.
Prime Minister Najib Mikati called for calm to be restored and warned against attempts to drag Lebanon into violence.