The body of an Afghan so desperate to escape the country hours after Kabul fell to the Taliban was found in the landing gear of an American C-17 transport aircraft hours after it hastily took off from Hamid Karzai International Airport, according to two sources familiar with the matter.

The U.S. Air Force said on Tuesday that it was investigating the circumstances surrounding human remains that were found in the wheel well of one of its C-17s that flew out of Kabul amid the chaos of the Taliban taking over the Afghan capital.

“Faced with a rapidly deteriorating security situation around the aircraft, the C-17 crew decided to depart the airfield as quickly as possible,” according to an Air Force statement.

“In addition to videos seen online and in press reports, human remains were discovered in the wheel well of the C-17 after it landed at Al Udeid Air Base, Qatar,” the statement said. “The aircraft is currently impounded to provide time to collect the remains and inspect the aircraft before it is returned to flying status.”

Three US officials told The Washington Post that after the plane’s landing gear would not go up, the crew investigated and later found the body in the wheel well.

Politico confirmed The Post’s report, citing two sources familiar with the matter.

There was chaos at Kabul’s Hamid Karzai International Airport on Monday after the Taliban seized the Afghan capital and retook power in a lightning-speed offensive.

Thousands of Afghans seeking to flee the Islamist group swarmed the runways, desperate to board planes transporting US personnel out of the country; all commercial flights were canceled.

In videos circulating on Monday, Afghans could be seen running alongside and clinging to a US plane as it taxied.

Watch it here: Youtube/Al Jazeera English

Other videos appeared to show people falling from planes to their deaths.

At least seven people were killed in the chaos, including people who fell from planes and two armed men shot by US troops, US officials told The Associated Press.

The U.S. resumed operations out of the airport late Monday, allowing C-17s carrying Marines and soldiers from the 82nd Airborne Division to land in the country, according to Maj. Gen. Hank Taylor, the Joint Staff’s deputy director for regional operations and force management.

Earlier in the day, U.S. forces responded to “hostile threats” after gunfire broke out in two separate incidents, resulting in the deaths of two gunmen, Kirby confirmed. One U.S. service member was injured during the incident, he said, but could not confirm the individual’s status late Monday.

Meanwhile, more than 600 Afghans crowded onto another C-17 — a number thought to be among the most ever flown in the military’s massive cargo jet, Defense One reported.

Sources: Business Insider, Politico, NBC News, Reuters