Dozens of civilians were killed in Aleppo as Russian and Syrian regime bombers pounded the besieged city with a wave of air strikes on a scale unprecedented in six years of war.
More than 150 air strikes have rocked the rebel-held eastern half of Aleppo since Saturday 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. Three centres used by the White Helmets, the volunteer Syrian Civil Defence, were bombed, according to Samantha Power, the US Ambassador to the UN.
The attack is believed a harbinger of an all-out ground assault to finally crush opposition in Syria's second largest city.