President Barack Obama issued a personal apology to the head of Doctors Without Borders on Wednesday in wake of a U.S. airstrike that killed 22 people at a Doctors Without Borders hospital in Kunduz, Afghanistan last weekend.

According to the U.S. military, the airstrike, which left 12 members of the Doctors Without Borders staff as well as 10 patients dead, was conducted on Saturday at the request of Afghan allies in need of assistance after coming under fire. However, U.S. Gen. John F. Campbell confessed on Wednesday that the attack was "a U.S. decision made within the U.S. chain of command," reports The New York Times.

The White House also announced on Wednesday that Obama called and apologized to Doctors Without Borders International President Joanne Liu for what he said was a mistaken U.S. bombing. Obama also promised a full investigation and vowed to cooperate with the joint investigations being conducted with NATO and the Afghan government.

"The President assured Dr. Liu that the Department of Defense investigation currently under way would provide a transparent, thorough and objective accounting of the facts and circumstances of the incident and, if necessary, the President would implement changes that would make tragedies like this one less likely to occur in the future," said White House Press Secretary Josh Earnest, according to CNN.

In response to Obama's apology, Liu released a statement calling for an independent investigation to look into the incident.

"We reiterate our ask that the U.S. government consent to an independent investigation led by the International Humanitarian Fact-Finding Commission to establish what happened in Kunduz, how it happened, and why it happened," said Liu.

After holding a conversation with Liu, Obama then called Afghan President Ashraf Ghani to express his condolences for the Aghan civilians who lost their lives in the airstrike. The president also spoke on behalf of the American people, offering his thoughts and prayers for the victims.

During the call, Obama and Ghani "reaffirmed their commitment to strengthening the partnership between the United States and Afghanistan and to continuing their dialogue about ways to deepen diplomatic, economic and security cooperation to promote a more stable and secure Afghanistan," said the White House.