The largest hospital in the rebel-held side of Syria’s Aleppo city on was hit at least twice by barrel bombs on Saturday, the medical organisation that supports it said.

The facility, known as M10, had previously been a target of heavy bombardment on Wednesday along with the second-largest hospital in the area.

Commenting on the act, U.N. chief Ban Ki-moon denounced it as “war crimes.”

After these attacks there are only six operational hospitals in the eastern parts of the city, as both facilities are put out of service, according to SAMS.

The Syrian Observatory for Human Rights, a British-based monitoring group, said air strikes also hit a smaller field hospital in the Sakhur neighbourhood on Saturday.

“One person was killed and the field hospital is out of service,” said Observatory head Rami Abdel Rahman, who couldn’t immediately approve if the victim was a patient at the facility or a staff member.

The World Health Organization has called Syria the most dangerous place in the world for health workers.