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The U.S. blamed the Syrian government Thursday for a direct airstrike on an Aleppo hospital that killed more than a dozen doctors and patients.

Two of the eight doctors working at the Al Quds hospital, which is located in rebel-held Aleppo and specializes in treating children, were killed in Wednesday's air attack, the Doctors Without Borders medical charity reported.

"These strikes were conducted by the regime, solely by the regime," State Department spokesman John Kirby said. "The facts are still coming but every indication we have seen so far points to the regime."

People inspect the damage at Al Quds hospital in Aleppo, Syria, on Thursday. ABDALRHMAN ISMAIL / Reuters

Secretary of State John Kerry blasted Syrian despot Bashar Assad for what "appears to have been a deliberate strike on a known medical facility" and called on his Russian allies to reign in the air attacks.

"Russia has an urgent responsibility to press the regime to fulfill its requirements," he said.

There was no immediate response from Assad, but his Russian ally insisted they did not carry out the deadly strike.

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"The data available to us shows that a plane of one of the countries of the so-called 'anti-ISIS' coalition has been operating in Aleppo airspace after a long period of inactivity," said Russian military spokesman Maj. Gen. Igor Konashenkov.

Konashenkov was referring to the U.S.-led coalition that has been bombarding ISIS-held territory in Syria.

Doctors Without Borders, which is also known as Médecins Sans Frontières, said it was "outraged" by the incident.

We condemn the destruction of the Al Quds hospital in #Aleppo, depriving people of essential healthcare. Hospitals are #notatarget, #Syria — MSF International (@MSF) April 28, 2016

“This devastating attack has destroyed a vital hospital in Aleppo,” spokesman Muskilda Zancada said in a statement. “Where is the outrage among those with the power and obligation to stop this carnage?”

Al Quds hospital had an eight-bed pediatrics unit and was "the main referral center" for ailing children, the charity said. It employed eight doctors and 28 nurses.

The hospital emergency room, intensive care unit, and operating room were reduced to rubble by the airstirke, according to the charity group.

A victim is carried from the hospital following the airstrike on Wednesday night. ABDALRHMAN ISMAIL / Reuters

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.

At least 3 doctors killed in attack on @MSF supported hospital including 1 of last pediatricians in #Aleppo. Hospitals #notatarget. #Syria — Jason Cone (@jtcone1977) April 28, 2016

Syria's five-year-long 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. And it has been badly damaged during the war, with many neighborhoods obliterated by bombings and much of its population forced to live without water and power for months.

A cease-fire was declared 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.

It's not the first time medical facilities affiliated with Doctors Without Borders have come under attack.

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.

In January, at least six people were killed after a projectile was fired at another hospital in northern Yemen.

In February, the charity said a "deliberate airstrike" on a hospital in the Syrian town of Maaret al-Numan killed at least seven people.