Lebanese protesters stormed the foreign ministry in Beirut on Saturday amid anger over the deadly blast this past Tuesday, AFP reported.
Thousands of demonstrators, some of them brandishing nooses, had descended on the city center to vent their fury at politicians they blame for the explosion, which levelled Beirut port and killed 158 people.
Amid the outpouring of rage, Prime Minister Hassan Diab said he would seek early elections, saying it was the only way to "exit the country's structural crisis".
Demonstrators marched through streets ravaged by the blast, gathering in the central Martyrs' Square, where a truck was on fire, as their grief gave way to anger.
As security forces fired tear gas to disperse stone-throwing demonstrators who tried to push their way toward parliament, a group led by retired Lebanese army officers stormed the foreign ministry and declared it the "headquarters of the revolution".
The Lebanese Red Cross said it had taken 55 people from the protest to nearby hospitals and treated another 117 at the scene, without specifying who they were.
Earlier this week, Lebanese security forces fired tear gas to disperse dozens of anti-government demonstrators angered by the Beirut blast.
Lebanese authorities said the Beirut explosion was triggered by a fire igniting 2,750 tons of ammonium nitrate negligently stored in a warehouse at the port since 2013.
This raised questions as to how such a huge cargo of the highly explosive substance could have been left unsecured for so long.
Lebanese President Michel Aoun said on Friday the investigation into the blast would examine whether it was caused by a bomb or other external interference.
“The cause has not been determined yet. There is a possibility of external interference through a rocket or bomb or other act,” Aoun was quoted told local media.
Aoun, who had previously said explosive material was stored unsafely for years at the port, said the investigation would also weigh if the blast was due to negligence or an accident.
The explosion came as Lebanon was already in its worst economic crisis since the 1975-1990 civil war.
The explosion added to the grievances of the protest movement that emerged in October to demand the removal of a political class deemed inept and corrupt.