A hospital, blood bank and ambulances are reported to have been hit as Syrian government aircraft and artillery bombarded rebel-held eastern Aleppo.
The director of the Bayan Children’s Hospital was forced to take shelter in the facility’s basement.
Activists say at least 32 people, including children, have been killed in Aleppo over the past two days.
The air strikes resumed on Tuesday after a three-week moratorium declared by the government’s ally Russia ended Activists confirmed the resumption of government air strikes, amid reports by state media of large troop deployments on several fronts ahead of a major ground assault.
The UK-based Syrian Observatory, a monitoring group, said missiles fired by jets, barrel bombs dropped from helicopters and artillery targeted several areas of eastern Aleppo on Wednesday, including Shaar, Sukkari, Sakhour and Karam al-Beik.
At least 21 people, including five children and an emergency worker, were killed, the group said.