Medics in the city are struggling to cope with the huge number of casualties caused by the most sustained and intense aerial bombardment in years.
Supplies of medicine and blood are running low, as a three-week siege by the army begins to have an impact.
An air strike on a pumping station has also left many areas without water.
"The planes are not leaving the skies at all," Brita Hagi Hassan, president of the rebel city council, told Reuters news agency. "Life in the city is paralysed."