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JALALABAD, Afghanistan — Twelve Doctors Without Borders staff along with seven patients, including three children, were killed after an apparent U.S. airstrike hit the international charity's hospital in the Afghan city of Kunduz.

Another 37 others were injured in the strike: 19 staff members, including five in critical condition, and 18 patients and caretakers, according to Jason Cone, the executive director for Doctors Without Borders in the U.S. The organization didn't comment on the identities of the victims, but said all international staffers were alive and accounted for.

Coalition spokesman Col. Brian Tribus confirmed that a U.S. airstrike conducted at around 2:15 a.m. local time on Saturday (5:45 p.m. ET Friday) "may have caused collateral damage to a nearby health facility." The incident was being investigated, he added.

A fire burns at the Doctors Without Borders trauma center in Kunduz, Afghanistan, early Saturday. Doctors Without Borders / Medecins Sans Frontieres

Tribus said the bombing was targeting "individuals threatening the force." The U.S. Embassy later described it as a "tragic incident."

Secretary of Defense Ash Carter said in a statement that U.S. forces, Afghan Security Force and Taliban fighters have all been active in the area surrounding the hospital, and “we are still trying to determine exactly what happened.”

Taliban militants seized control of Kunduz earlier this week but the Afghan government said Thursday that its forces were in "full control" of the city, which is home to 300,000 people.

The Afghan military also said that the U.S. conducted a 2:15 a.m. airstrike “against insurgents who were directly firing upon U.S. service members.” Gen. John F. Campbell, Commander of U.S. Forces in Afghanistan, said he spoke with Afghan President Mohammad Ashraf Ghani.

“Both the President and Gen. Campbell agreed to launch a joint and thorough investigation,” said a statement from the president’s office. “President Ghani reiterates that the Afghan and foreign forces alike must put in serious efforts not to target public places in military operations,” the statement said.

President Barack Obama offered his condolences to the victims and said he will be kept updated on any developments into the investigation of the bombing. "The Department of Defense has launched a full investigation, and we will await the results of that inquiry before making a definitive judgment as to the circumstances of this tragedy," he said in a statement Saturday night.

Doctors Without Borders — which is also known as Medecins Sans Frontieres — said its site "was hit several times during sustained bombing and was very badly damaged." It called the incident an "aerial attack."

Shocked #MSF staff in one of remaining parts of MSF's hospital in #Kunduz. First aid ongoing http://t.co/Ch4wT5ef7c pic.twitter.com/I54mDTwpTm — Kate Stegeman (@KatesCurious) October 3, 2015

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“The bombs hit and then we heard the plane circle round. There was a pause, and then more bombs hit,” Heman Nagarathnam, MSF’s head of programs in northern Afghanistan, said in a statement. “Patients who were unable to escape burned to death as they lay in their beds,” he said.

A nurse who was asleep in a hospital safe room during the airstrike described the shock he felt when he emerged after the bombings ended and saw the destruction. "The first moments were just chaos. Enough staff had survived, so we could help all the wounded with treatable wounds. But there were too many that we couldn't help," wrote nurse Lajos Zoltan Jecs in a statement released by MSF.

A patient was on the operating table when the bombing occurred and forced staff to flee, Vickie Hawkins, executive director of Doctors Without Borders UK told NBC News. The patient died.

Related: Will Taliban Invasion Keep U.S. Boots on Ground in Afghanistan?

Dalila Mahdawi, a spokeswoman for the charity, said that "all parties to the conflict, including in Kabul and Washington, were clearly informed of the precise location (GPS coordinates)" of its hospital and other facilities in the area.

"The bombing continued for more than 30 minutes after American and Afghan military officials in Kabul and Washington were first informed," Mahdawi added.

From 2:08 until 3:15 AM local time today, our hospital was hit by a series of aerial bombing raids at approx 15 minute intervals #Kunduz — MSF International (@MSF) October 3, 2015

“This attack is abhorrent and a grave violation of International Humanitarian Law,” added MSF President Meinie Nicolai said in a statement. "We demand total transparency from Coalition forces. We cannot accept that this horrific loss of life will simply be dismissed as ‘collateral damage.'"

Nicolai said that on top of the devastating loss of life, the “attack has cut off access to urgent trauma care for the population in Kunduz at a time when its services are most needed.” The hospital is the only medical facility of its kind in the northeastern region of Afghanistan, according to the aid agency.

In addition to the twelve workers killed, 37 other people were seriously wounded by the bombing — including 19 staff members.

Fires burn in part of a Doctors Without Borders hospital in the Afghan city of Kunduz on Saturday. Doctors Without Borders / Medecins Sans Frontieres / AFP - Getty Images

At the time of the incident, the clinic had 105 patients and their caretakers, and more than 80 international and Afghan staff were present, the charity said.

Adil Akbar, a doctor at the trauma center who was on duty at the time, told The Associated Press that the operating theater, emergency room and other parts of the hospital complex had been hit in the bombing.

"I managed to escape after the attack but I know that most of the staff and even some of the patients are missing," Akbar said.

“Patients who were unable to escape burned to death as they lay in their beds.”

Doctors Without Borders said it had treated 394 people who had been injured since fighting began on Monday when Taliban militants conquered the provincial capital in a stunning setback for the Western-backed government. It was the first major urban area to fall to the Taliban since the U.S.-led invasion of Afghanistan in 2001.

Interior Ministry spokesman Sediq Sediqqi told NBC News that up to 15 militants had "taken position inside the hospital compound" and begun firing on Afghan forces.

"There was an operation conducted to eliminate the threat. The hospital has been damaged and there are some casualties," Sediqqi added. "All of the terrorists were killed, but we also lost doctors."

The Doctors Without Borders clinic in Kunduz is a sprawling facility with numerous buildings situated in the east of the city, in a residential area close to the local office of the NDS intelligence service.

The U.S. Embassy released a statement saying it was mourning "the individuals and families affected by the tragic incident at the Doctors Without Borders hospital."

“International and Afghan military planners have an obligation to respect and protect civilians at all times, and medical facilities and personnel are the object of a special protection,” U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein said in a statement Saturday.

“This event is utterly tragic, inexcusable, and possibly even criminal,” Al Hussein said. “The seriousness of the incident is underlined by the fact that, if established as deliberate in a court of law, an airstrike on a hospital may amount to a war crime."