Syrian government air raids using barrel bombs on rebel-controlled areas of Syria's second city of Aleppo at the weekend killed at least 76 people, including 28 children, activists said.
Activists reported on Monday that four women were also among the dead, a day after regime helicopters dropped barrels filled with explosives on civilian rebel-held districts in the northern city.
A previous toll from the Syrian Observatory for Human Rights- which relies on a network of activists, lawyers and medics for its information - had put the number of killed at 36, among them 15 children.
The Aleppo Media Centre, a network of activists on the ground, called the raids on the northern city unprecedented".
Footage uploaded by local activists on social media showed a fire in a narrow street covered in debris and dust after one air raid in the Karam el-Beik district.
Other videos showed people carrying the injured in blankets and bulldozers removing debris in a destroyed neighbourhood.
Civil defence volunteers told Al Jazeera they had not rested since the morning as they tried to cope with the bombardment.
Over the next few days, we will be sending to Qamishli... 400 tonnes of food.
"More than 10 different areas in Aleppo came under heavy bombardment," one member of the team told Al Jazeera.
"They were shelled by both explosive barrels and missiles."
In an interview with Al Jazeera's Darren Jordon, Andrew Tabler, a Syria analyst at the Washington Insititute for Near East Policy, said the latest attack shows the determination of the Assad regime to retake Aleppo.
"The Assad regime has the troops to retake the area," Tabler said. "The question is if they have enough troops to hold it."
Near the capital, the Observatory said that death toll has risen to 28 people in the town of Adra, northeast of Damascus, after a rebel faction launched an assault there on Wednesday.
Observatory director Rami Abdurrahman said the dead were primarily members of President Bashar Assad's minority Alawite sect, as well as a few Druze and Shia Muslims. All three sects largely support Assad in the fight against the mainly Sunni rebels.
Meanwhile, the United Nations sent its first delivery of humanitarian aid by air to Syria from Iraq on Sunday and said it plans to deliver more food and winter supplies to the mainly Kurdish northeast in the next 12 days.
The first cargo plane carrying food took off from Arbil in Iraq's northern Kurdistan region heading to Hassakeh in Syria.
The food supplies over the next 12 days should be able to feed more than 6,000 Syrian families for the rest of December, the UN's World Food Programme said. This is the third winter since the Syrian conflict began in March 2011.
"We witnessed today the first flight that took place from Arbil International Airport to Qamishli city, which is populated by Kurdish inhabitants in Syria. This is the first flight to be conducted in this manner," Dindar Zibari, deputy head of Kurdistan's Foreign Relations Department, told journalists at the airport.
The 12-day airlift, involving various UN agencies, will include 400 tonnes of food and 196 kg of medical kits, he said.
"We hope also by the beginning of January this air shipment and air cargo will continue to Syria. This is something the KRG (Kurdistan Regional Government) fully supports because it will possibly reach the most needy vulnerable families inside Syria," he added.
Both governments gave permission for the aid flights which will also include supplies of non-food items such as blankets, clothes and medicine in the coming days.