The carnage occurred as Russian-backed Syrian troops intensified their push toward the rebel stronghold of Aleppo.
Fourteen people were killed in the town of Azaz near the Turkish border when missiles slammed into a school sheltering families fleeing the offensive and a children's hospital, two residents and a medic said on Monday.
Bombs also hit another refugee shelter south of the town and a convoy of trucks, another resident said.
"We have been moving scores of screaming children from the hospital," medic Juma Rahal said.
At least two children were killed and scores of people injured, he said.
A man receives treatment at a make-shift hospital, following a reported airstrike on the besieged rebel-controlled city of Douma, a flashpoint near the Syrian capital on February 15, 2016. Source: Getty Images
Activists posted video online purporting to show the damaged hospital. Three crying babies lay in incubators in a ward littered with broken medical equipment. Reuters could not independently verify the video.
In a separate incident, missiles hit another hospital in the town of Marat Numan in Idlib province, in northwestern Syria, said the French president of the Doctors Without Borders/Mdecins Sans Frontires (MSF) charity, which was supporting the hospital.
#Idlib: The latest incident in a horrific string of attacks that targeted hospitals in Syria https://t.co/Vcp9M29Pjf pic.twitter.com/V955AiPebW — MSF International (@MSF) February 15, 2016
"There were at least seven deaths among the personnel and the patients, and at least eight MSF personnel have disappeared, and we don't know if they are alive," Mego Terzian told Reuters.
"The author of the strike is clearly ... either the government or Russia," he said, adding that it was not the first time MSF facilities in Syria had been attacked.
The Syrian Observatory for Human Rights, which tracks violence across the country, said one male nurse was killed and five female nurses, a doctor and one male nurse are believed to be under the rubble in the MSF hospital.
Also in Marat Numan, another strike hit the National Hospital on the north edge of town, killing two nurses, the Observatory said.
United Nations Secretary-General Ban Ki-moon said the attacks, which the UN said killed close to 50 civilians, were a blatant violation of international laws.
"These incidents cast a shadow on the commitments made at the ISSG (International Syria Support Group) meeting in Munich on February 11," UN spokesman Farhan Haq said.
The United States also condemned the intensified bombing of northern Syria and said it ran counter to commitments made by world powers in Munich last week to reduce hostilities.
Residents in both towns blamed Russian strikes, saying the planes deployed were more numerous and the munitions more powerful than the Syrian military typically used.
A handout imageshowing destruction and rubble at an MSF-supported hospital in Idlib province in northern Syria, largely destroyed in an attack on early 15 February 2016. Source: AAP
