The US Air Force has said it is investigating the circumstances that led to the human remains being found in the wheel well of one of its C-17s that flew out of Kabul amid the chaos at the airport as scared Afghans swarmed the runway to escape the wrath of the Taliban.

The remains were discovered in the wheel well of the plane after it landed in Qatar, Air Force spokeswoman Ann Stefanek said in a statement. The Air Force is also examining videos and social media posts of people falling from the plane after its takeoff.

The plane had landed at Kabul airport with equipment needed for the evacuation of civilians.  However, before it could be unloaded, hundreds of Afghan civilians surrounded it and clung to its fuselage.

American forces had to fire in the air at the Kabul airport on Monday to prevent desperate Afghans running onto the tarmac to board military flights in an attempt to flee from the Taliban.

US military planes are flying out at-risk Afghans in large numbers. Photos of a US Air Force's C-17 Globemaster III transport plane crammed with hundreds of scared Afghans sitting on the floor of the aircraft have gone viral on social media.

The aircraft took a total of 640 Afghans, believed to be among the most people ever flown in the C-17, according to the news website Defense One.

The plane flew to Qatar, where the Afghans disembarked, the website reported. None of them including women and children appear to be carrying any luggage as they left in a last-minute desperate dash to save their lives when the Taliban suddenly walked into Kabul. The picture of the packed flight depicts the tragic chaos that Afghanistan has descended into in a matter of days. 

Video clips also show two US Apache attack helicopters flying low over the tarmac to disperse the crowd and clear the runway for the C-17's take-off run.

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