At least 14 patients and three doctors have been killed in an air strike on a hospital in the Syrian city of Aleppo, the charity Medecins sans Frontieres (MSF) says.
Among those killed in the MSF-supported al-Quds hospital was one of the city’s last paediatricians, MSF said.
Local sources have blamed the Syrian government or Russian war planes, but there has been no official comment.
Monitors say attacks by both sides left 34 dead and dozens wounded on Thursday.
Violence in Syria has intensified in recent days, despite a partial truce.
The upsurge in violence comes amid reports that the Syrian army, backed by Russian air power, is gearing up for a major offensive in Aleppo.
The escalation has threatened to derail the UN-brokered peace talks, which resumed last month.
On Wednesday, the UN envoy to Syria urged the US and Russia to intervene “at the highest level” to save the talks.