Dozens of civilians were killed in Aleppo yesterday (Sunday) as Russian and Syrian regime bombers pounded the besieged city with a wave of air strikes on a scale unprecedented in Syria's six years of war.
More than 150 air strikes have rocked the rebel-held eastern half of Aleppo since Friday including the use of massive "bunker buster" bombs and incendiary devices that can set fire to whole streets, the US said.
At least 140 people have been killed in the attacks over the weekend and Save the Children estimated that around half of the casualties were children. At least six children were reported to have been killed by a barrel bomb attack yesterday.
One photograph from the city showed a mother's body buried in the rubble while cradling a small baby. A dead boy lay behind them tucked a little further into the ruined building.
The city's few remaining functioning hospitals were overwhelmed with casualties and doctors said patients were dying on the floor in hallways because there were too few staff and supplies to treat them.
"I've never seen so many people dying in once place," said Mohammad Zein Khandaqani, a member of the medical council which oversees hospitals in the rebel areas.
The US also accused Russian and the Syrian regime of deliberately targeting rescue workers in "double tap" strikes, where an aircraft bombs an area and then strikes again minutes later to kill first responders who attend the scene.
Three centres used by the Syrian Civil Defence, a volunteer rescue organisation better known as the White Helmets, were bombed over the weekend, according to Samantha Power, the US ambassador to the UN.
She warned that the result of attacks on rescue workers would be more civilians left to die in the ruins of their homes.
"Those buried alive in rubble in eastern Aleppo are much more likely to die in rubble," she told the UN security council.
The unprecedented attack from the air is believed a harbinger of an all-out ground assault by Bashar al-Assad's forces to finally crush opposition in Syria's second largest city.
The Syrian regime military announced on Friday that it was preparing an offensive to finally retake east Aleppo, where around 275,000 people have lived under rebel and jihadist control since 2012.
The army urged civilians inside the rebel bastion to try to flee and surrender themselves to Syrian Arab Army checkpoints. Syria's military is bolstered by Russian air power but also ground troops from Iran and the Hizbollah militant group.
Staffan de Mistura, the UN special envoy for Syria, warned the Syrian regime against such an attack, saying that it would only lead to more devastation in the city.
"It's going to be a slow, grinding, street-by-street fight over the course of months, if not years, whereby the ancient city will be almost completely destroyed," he said.
Much of the ground fighting yesterday focused on Handarat, a Palestinian refugee camp in the which is now largely abandoned after it was repeatedly taken and retaken by the opposing sides.
Rebel forces lost control of the camp to advancing regime troops over the weekend after coming intensive airstrikes but retook the area in fighting late on Saturday night.