With the Taliban growing more violent and adding checkpoints near Kabul's airport, an all-volunteer group of American veterans of the Afghan war launched a final daring mission on Wednesday night dubbed the "Pineapple Express" to shepherd hundreds of at-risk Afghan elite forces and their families to safety, members of the group told ABC News.

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 Pineapple Express' mission was underway Thursday when the attack occurred in Kabul. Two suicide bombers believed to have been ISIS fighters killed at least 13 U.S. service members -- 10 U.S. Marines, a Navy corpsman, an Army soldier and another service member -- and wounded 15 other service members, according to U.S. officials.

snip...

After succeeding with helping dozens of Afghan commandos and interpreters get into the protective ring of the airport created by the 6,000 American troops President Joe Biden dispatched to the airfield after Kabul fell to the Taliban, the group initiated an ambitious ground operation this week aided by U.S. troops inside. The objective was to move individuals and families through the cover of darkness on the "Pineapple Express." The week-long effort and Wednesday's operation were observed by ABC News under the agreement of secrecy while the heart-pounding movements unfolded.