The Syrian regime and Russia have stepped up strikes on Sunday on opposition-held east Aleppo where more than 250,000 civilians are living under a regime siege.
Aleppo had been Syria’s economic powerhouse until the civil war in the country broke out 2011. Control over the city has been roughly divided between the regime in the west and the opposition in the east.
The eastern section of the city has been under near-continuous siege since mid-July.
A ceasefire was declared two weeks ago but fell apart in the past week before any aid reached the besieged areas in Aleppo.
On Thursday the Syrian regime announced its forces were beginning an operation to take control of eastern Aleppo. Since then, at least 101 people, mostly civilians, have been killed in escalating violence, according to the Syrian Observatory for Human Rights (SOHR).
The monitor said at least 17 children were among those killed.
According to residents, the assaults include missile strikes, barrel bomb attacks, artillery fire and cluster munitions.
"All night long they were dropping cluster bombs. I couldn't sleep until four in the morning," said Ahmed Hajar, a 62-year-old Aleppo resident who was out looking for bread in Al-Kalasseh neighbourhood.
"Today the streets of my neighbourhood are full of unexploded cluster bombs. One person was killed when he disturbed one and it exploded," he added.
The reports came hours before a United Nations Security Council meeting which will discuss the violence – the worst to hit Aleppo in years.
The emergency session, which was called by the US, the UK and France, will be held in New York at 1500 GMT. However, the stance of the Syrian regime and Russia appears to have buried any hope for a diplomatic solution.
On Saturday, regime Foreign Minister Walid Muallem said the regime is confident of "victory" with the support of its "true friends."
More than 300,000 people have been killed and over half the country displaced since the war began in March 2011.
Successive attempts to reach a political solution have failed. Washington had worked hard to negotiate a peace agreement with Moscow in talks which produced two ceasefires. Both proved short-lived.