Human remains found in wheel well of C-17 military plane that departed from Kabul

The U.S. Air Force has confirmed that human remains were found inside the wheel well of a C-17 military plane that had been swarmed by hundreds of people on the tarmac as it took off at Hamid Karzai International Airport in Kabul.

The discovery was made upon landing at al Udeid Air Base in Qatar on Monday.

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A dramatic video taken earlier Monday showed some people clinging to the plane as it taxied down the runway in Kabul.

A defense official said the individuals swarming the plane had breached the runway from the civilian side of the airport. At the airport in Kabul, there is a side for military operations and another side for commercial flights.

Air operations were suspended for hours at the airport Monday because of the crush of Afghan civilians desperate to leave Kabul. Operations resumed after the U.S. military, Turkish forces and other troops forcibly removed 15,000 Afghan civilians who had breached the runway, a U.S. official said.

The Air Force's Office of Special Investigations is reviewing the incident in coordination with the Air Force's Air Mobility Command and international partners.

"OSI is leading the review in coordination with the U.S. Air Force's Air Mobility Command and international partners since it involves the loss of life on U.S. military aircraft," Air Force spokesperson Ann Stefanek said in a statement. "OSI's review will be thorough to ensure we obtain the facts regarding this tragic incident. Our hearts go out to the families of the deceased."

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The C-17 had landed on a runway at the airport earlier in the day with a load of cargo, according to a summary of events from the Air Force. After landing, the pilots were surprised when the crew attempted to unload its cargo and it was rushed by hundreds of Afghan civilians. At that point, the aircrew decided it was not safe to unload and began taxiing to fly away to safety.

The aircraft was impounded to provide time to collect the remains and inspect the plane before it's returned to flying status.

"Alongside our joint force, interagency and international partners, the U.S. Air Force remains laser-focused on maintaining security at (the Kabul airport) to prevent a situation like this from happening again as we safely process Afghan civilians seeking to depart the country," the Air Force statement said.

U.S. Pentagon press secretary John Kirby said Tuesday the U.S. will soon have the capacity to evacuate 5,000 to 9,000 individuals a day now on a mix between commercial and military aircraft -- but a lot of that depends on if the Taliban will allow those commercial planes to fly.

The White House said Tuesday that both sides of the airport are open and operational with flights able to land and depart. There were 3,500 U.S. troops on the ground to help control airport operations as of Tuesday morning.

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On Monday, more than 700 people were evacuated by the U.S. military, including 165 American citizens, the Pentagon said.

Kirby, at a briefing with reporters Monday, was matter of fact, saying the crush of civilians at the airport came about because "there were a lot of Afghans that wanted to get out of the country."

ABC News' Libby Cathey and Lauren King contributed to this report.