Volunteer first responders in Syria's Aleppo have pulled the bodies of nine people, including four children, from the rubble following air raids Friday on a rebel-held district.   

The Syrian Civil Defense, also known as the White Helmets, said helicopters dropped crude barrel bombs on the area. The activist-operated Aleppo Media Center and the Local Coordination Committees also reported that nine were killed in the bombing. The LCC said five were wounded and rescuers continued to sift through the rubble for survivors.   

The U.N. humanitarian chief Stephen O'Brien described the situation in rebel-held eastern Aleppo as "extremely severe, to the point of it being de facto besiegement." Aleppo, Syria's largest city and onetime commercial center, has been divided since 2012.   

Speaking in Geneva with the U.N. Syria envoy Staffan de Mistura, O'Brien said the international body will continue to press for a 48-hour weekly humanitarian pause. Some 250,000 people are estimated to be trapped in the rebel-held eastern Aleppo.   

Efforts to bring about a nationwide cease-fire and a return to peace talks are currently bogged down over Aleppo, which has seen months of intense fighting.   

U.S. Secretary of State John Kerry is meeting with his Russian counterpart in Geneva Friday to discuss such a deal, in talks that have dragged over two weeks.  

A deal hinges on an unlikely U.S.-Russian military partnership that would come into force if Moscow can pressure its ally, Syrian President Bashar Assad's government, to halt offensive operations. Washington would have to persuade the anti-Assad rebels it supports to end any coordination with al-Qaida's affiliate in Syria and other extremist groups.   

De Mistura said if the U.S-Russia talks succeed it could make a "major difference."   

"We are all hoping for positive conclusions. Let's be frank: the discussions are addressing complex, delicate, difficult issues," said de Mistura, who met with Lavrov Thursday.   

De Mistura reiterated the concerns over the situation in eastern Aleppo, saying the area may run out of fuel within days. "So regardless of everywhere, Aleppo is becoming an urgent issue even more than before."   

Pro-government forces have recently stepped up attacks on rebel-held Aleppo, after regaining control this week of a major artery in the city's south, which rebel forces had taken last month.   Friday's air raids on the city's southern edge came after a wave of bombings, including suspected gas attacks, blamed on the government.   

A women and children's hospital in eastern Aleppo was briefly shut down after it was hit in an air raid late Tuesday, making it the latest of the area's eight hospitals to be damaged since July in the bombing campaign, Doctors Without Borders said Friday.