Shells slammed into a densely-populated Tripoli suburb overnight in the latest attack of a two-week assault by commander Khalifa Haftar's forces in an effort to take Libya's capital from the United Nations-backed government.
The explosions, just before midnight Tuesday, hit the southern residential district of Abu Salim near a disused airport.
More than 800 people have been wounded since Haftar attempted to seize the capital city.
"Horrible night of random shelling of residential areas. For the sake of three million civilians living in Greater Tripoli, these attacks should stop. NOW!" tweeted U.N. envoy Ghassan Salame, who is in Tripoli and has been pushing a peace plan in vain
Haftar and his eastern Libyan forces have cast their advance as part of a campaign to restore order in a nation that has been engulfed in turmoil since a United States-backed NATO intervention ousted Muammar Gaddafi in 2011.
The United Nations' humanitarian agency the OCHA said thousands of civilians were trapped in southern districts of Tripoli due to the fighting.
“The indiscriminate attacks showed his forces lacked a shred of humanity,” said Tripoli’s government denouncing the attack.
The prime minister, Fayez al-Sarraj visited the sites Wednesday. Calling for three days of mourning, the prime minister said the evidence of an attack on the civilian neighborhood will be handed over to the International Criminal Court (ICC).
Fatou Bensouda, the chief prosecutor at the ICC, said she would bring charges against the responsible party.
“I remind all parties that any person who incites or engages in such crimes including by ordering, requesting, encouraging or contributing in any other manner to the commission of crimes within the jurisdiction of the court is liable to prosecution,” Bensouda said in a statement.
The Tripoli government will launch a counter-offensive against Haftar’s Libyan National Army (LNA) in eastern Libya and try to seize control of the city of Benghazi which is under LNA.
However, more than being aghast about piling bodies, International powers are aghast at the flare-up in Libya which threatens to disrupt oil supplies from the OPEC nation and may unleash a new wave of migration across the Mediterranean to Europe.
Italy's far-right Interior Minister Matteo Salvini said Haftar's offensive had heightened the risk of militants joining migrant boats in the Mediterranean heading for his country.
But no common position has emerged given different sympathies towards the factions around the Arab Gulf and Europe. Saudi Arabia, Egypt and the United Arab Emirates are backing Haftar's offensive while Turkey and Qatar are backing the internationally-recognized government which risks turning the most recent escalation in Libya into another proxy war between competing regional powers.