1 Woman Killed, Several Children Injured After Airstrikes in Aleppo

— LONDON -- One woman was killed and several children were injured after airstrikes pounded the city of Aleppo, according to residents and activists.

On Sunday, warplanes targeted the besieged Syrian city for the first time since the cease-fire went into effect last week, according to the Syrian Observatory for Human Rights.

The 52-year-old woman died after a wall fell on her after airstrikes on her house, according to Abu Rajab, a radiologist and managing director of the hospital where she was treated in Aleppo's al-Sakhur neighborhood.

"She had a head injury and suffered suffocation," Abu Rajab, told ABC News.

Four children were also treated at the hospital, he said. Among them was a 15-year-old girl who had pieces of shrapnel in her chest.

"She was experiencing severe pain and is still under observation at the hospital," Abu Rajab said.

Another child, a 3-year-old girl, was injured in the scalp and right hand.

"We give children gifts to help them relax. I gave her a toy train so that she could play with it and forget her pain," Abu Rajab said, adding that the girl remains in the hospital.

Two other children, a 3-year-old and a 2-year-old, were treated at the hospital and have been discharged, according to Abu Rajab.

"They had lighter wounds and stayed for one day," he said. "They had dust in their lungs and we gave them oxygen."

The U.S.-Russian-brokered cease-fire agreement was focused on reducing violence in the war-torn region and delivering humanitarian aid. The agreement had to be met before Russia and the U.S. would work together to fight militant groups ISIS and al-Nusra in Syria.

So far no aid has entered eastern Aleppo, where up to 275,000 people live under siege, according to the United Nations. Two U.N. trucks carrying flour and food supplies that could feed around 185,000 people for one month are still parked by the Turkish border, ready to go.

"I am pained and disappointed that a United Nations convoy has yet to cross into Syria from Turkey, and safely reach eastern Aleppo, where up to 275,000 people remain trapped without food, water, proper shelter or medical care," Stephen O’Brien, U.N.'s undersecretary-general for humanitarian affairs and emergency relief coordinator, said in a statement today. "All parties must facilitate regular and sustained access to families in all the besieged and hard-to-reach areas across the country, through both cross-line and cross-border routes. The people of Syria have suffered long enough. Millions of Syrian civilians continue to face horrific deprivation and violence, especially those trapped in besieged and hard-to-reach areas."

Aid workers have not been able to reach eastern Aleppo since clashes between the Syrian government and armed rebel groups started on July 7.

Around 13.5 million people in Syria are in need of humanitarian assistance, while 4.8 million have fled their country and 6.1 million are internally displaced, according to this month's figures from the U.N.'s Office for the Coordination of Humanitarian Affairs.