At least 14 doctors and patients were killed after a direct airstrike destroyed a hospital specializing in pediatrics in Syria, the medical charity supporting the facility said Thursday.
Doctors Without Borders said at least three of the eight doctors working at the Al Quds hospital in a rebel-held area of Aleppo were killed in Wednesday night's attack.
It was not immediately clear who was behind the bombing.
A Syrian military source told Reuters that government warplanes had not been used in areas where airstrikes were reported. The defense ministry of Russia, which is conducting airstrikes in Syria to support President Bashar Assad, could not be reached for comment, according to the news agency. A U.S.-led coalition is also conducting airstrikes in the country.
Doctors Without Borders, which is also known as Médecins Sans Frontières, said it was "outraged" by the incident.
"This devastating attack has destroyed a vital hospital in Aleppo," Muskilda Zancada, MSF head of mission for Syria, said in a statement. "Where is the outrage among those with the power and obligation to stop this carnage?"
The hospital featured an eight-bed paediatrics unit and was "the main referral center" for ailing children, the charity said. The facility employed eight doctors and 28 nurses. Following the airstrike there was little left of the emergency room, intensive care unit, and operating room, according to the organization.
The International Committee of the Red Cross said the hospital had been "completely destroyed" and labeled the attack "unacceptable."
Marianne Gasser, head of the ICRC mission in Syria, noted in a statement that "sadly this is not the first time the lifesaving medical services have been hit."
Syria's Civil Defense rescue service in Aleppo, commonly known as the White Helmets, told NBC News that 30 people had been killed in the attack, including a nurse and her entire family.
Syria's five-year civil war has claimed at least 250,000 lives.
Aleppo is the country's second largest city, with a population of some 3.5 million, according to the CIA's World Factbook. It has been one of the war's worst affected metropolitan areas, with many neighborhoods suffering heavy damage and swathes of its population without water and power for months.
A cease-fire was called on Feb. 27 but United Nations Special Envoy Staffan de Mistura told reporters Thursday that this deal was "barely alive" after a recent rise in violence, Reuters reported.
In October, U.S. forces carried out what the charity called a "relentless and brutal aerial attack" on its hospital in the Afghan city of Kunduz, killing at least 42 people.
Doctors Without Borders called the incident a war crime and it drew apologies from President Barack Obama and the top U.S. commander in Afghanistan, who called it a "tragic mistake." The findings of a military investigation into the bombing will be released Friday, multiple defense officials told NBC News.
At least six people were killed after a projectile was fired at another hospital in northern Yemen in January, the third of its Yemeni hospitals to come under attack in the previous three months.
In February, the charity said a "deliberate airstrike" on a hospital in the Syrian town of Maaret al-Numan killed at least seven people.
This story originally appeared on NBCNews.com.