(NEXSTAR) – An operator communicating with the crew of a packed C-17 cargo jet at Kabul’s airport was just as shocked as anyone after learning how many evacuating Afghans had climbed aboard, according to an apparent audio exchange recorded before the flight.

On Sunday, the Air Force C-17 Globemaster III safely evacuated 640 Afghans who had been cleared to evacuate the country, despite the C-17 Globemaster III having a capacity of only 134 passengers, Reuters reported.

The Department of Defense has since confirmed the flight never intended to carry such a large volume of Afghans leaving Kabul, but “the crew made the decision to go” after panicked refugees crowded into the plane via a half-open ramp, according to a defense official cited by Defense One.

A photo from the inside the cargo plane, which began circulating earlier this week, shows hundreds of the evacuees inside the aircraft. But an apparent audio recording between the plane’s operators suggests that even the pilots were unaware of just how many people they were carrying.

In the audio, which has been cited by CNN and The Washington Post, an unidentified voice coordinating the flight is thought to be heard communicating with the cockpit.

“How many people are on your jet,” asks the unidentified person, who is soon taken aback by the estimate. “800 people on your jet? Holy… Holy cow.”

Despite the overestimate, it’s rare that a C-17 military transport aircraft would carry as many as 640 people like the C-17 on Sunday. One notable instance occurred in 2013,  when a C-17 evacuated more than 670 people fleeing a typhoon in the Philippines. A photo of that, too, was shared by the U.S. Air Force at the time.

More than 670 residents of Tacloban City, in the Philippines, were evacuated to Manila on a C-17 Globemaster III in 2013 during Super Typhoon Haiyan. (U.S. Air Force)

The unidentified defense official who spoke with Defense One also said it was likely that other military transport planes had left from Kabul’s airport on Sunday or Monday with hundreds of evacuees on board, and perhaps some with even more than 640 passengers.

Evacuating Afghans swarmed many of the departing military flights after the Taliban seized control of the capital after capturing all of the country’s major cities in a matter of days. U.S. military officials confirmed that several people died during chaotic scenes at the airport, including multiple who tried clinging to planes and fell, the Associated Press reported. The Air Force further said it would be investigating reports of human remains found in the landing gear of a C-17 cargo plane that left from Kabul’s airport on Monday, Reuters reported.

The Associated Press contributed to this report.