As the Biden administration has faltered in its withdrawal efforts amid the Taliban's takeover of Afghanistan, an all-volunteer group of former U.S. military veterans has been working tirelessly to secretly bring hundreds of Afghan elite forces and their families to safety.

What are the details?

In a featured write-up published Friday, ABC News detailed the daring mission, put on by "Task Force Pineapple," which over the past 10 days saved the lives of roughly 630 Afghan nationals who — should they have remained trapped inside Afghanistan — would have been targeted by Taliban fighters.

The mission reached its climax on Wednesday night when the group of volunteer veterans commenced operation "Pineapple Express" — modeled after Harriet Tubman's Underground Railroad — to slowly maneuver Afghan individuals and families through Taliban checkpoints and into U.S. military command.

The mission was underway Thursday when terrorist attacks carried out by ISIS fighters at the Kabul airport left at least 13 U.S. service members and 60 Afghans dead, with hundreds more injured. Some of the task force's members were among the wounded. Yet in spite of the deadly assault, the group pressed on:

Moving after nightfall in near-pitch black darkness and extremely dangerous conditions, the group said it worked unofficially in tandem with the United States military and U.S. embassy to move people, sometimes one person at a time, or in pairs, but rarely more than a small bunch, inside the wire of the U.S. military-controlled side of Hamid Karzai International Airport.

The effort ... reached a crescendo this week with dozens of covert movements coordinated virtually on Wednesday by more than 50 people in an encrypted chat room, which [Army Lt. Col. Scott Mann] described as a night full of dramatic scenes rivaling a "Jason Bourne" thriller unfolding every 10 minutes.

The small groups of Afghans repeatedly encountered Taliban foot soldiers who they said beat them but never checked identity papers that might have revealed them as operators who spent two decades killing Taliban leadership.

"Dozens of high-risk individuals, families with small children, orphans, and pregnant women, were secretly moved through the streets of Kabul throughout the night and up to just seconds before ISIS detonated a bomb into the huddled mass of Afghans seeking safety and freedom," Mann, a retired Green Beret commander who led the operation, recounted.

"This Herculean effort couldn't have been done without the unofficial heroes inside the airfield who defied their orders to not help beyond the airport perimeter, by wading into sewage canals and pulling in these targeted people who were flashing pineapples on their phones," he added.

What else?

In a move criticized by many, the Pentagon has not permitted uniformed U.S. service members to venture outside of the airport's perimeter to rescue Americans and Afghans seeking U.S. protection. But non-uniformed individuals, including former Navy SEAL Jason Redman, have not faced those same restrictions.

Redman, one of Task Force Pineapple's members, spent Wednesday night shepherding Afghans he knew to safety.

"The whole night was a roller-coaster ride," he recalled. "People were so terrified in that chaotic environment. These people were so exhausted, I kept trying to put myself in their shoes."

Looking back at the effort, however, Redman's sense of pride and accomplishment was tainted by disappointment, especially with the political leaders who allowed the situation to unravel to the point that it did only to, in his opinion, not do enough to resolve it.

According to ABC, he expressed deep frustration "that our own government didn't do this. We did what we should do, as Americans."