(NewsNation) — Family members of the 13 American service members killed during the pullout from Afghanistan in 2021 spoke out at a congressional hearing Monday, demanding accountability and answers.

“I feel I deserve real answers, real truths, facts and for someone to be accountable for the failures that occurred, that took my son’s life,” said Gold Star mother Cheryl Rex.

The service members, along with 170 Afghan civilians, were killed after an ISIS member detonated a suicide bomb just outside the Kabul airport, as the U.S. military tried to evacuate American and Afghan allies from the country.

Gold Star family members including Christina Shamblin, mother of Sgt. Nicole Gee, expressed their pain and anger at a meeting Monday.

“When our leaders, including our secretary of defense and our Commander in Chief call this evacuation a success as if there should be celebration, it is like a knife in the heart for our families and for the people who came back,” Shamblin said.

During the emotionally charged day, one father of a service member who was killed demanded accountability from the Biden administration.

“I’m calling out Secretary Blinken and Secretary Austin, General Milley. General McKenzie. You all need to resign immediately,” said Gold Star father Darin Hoover.

The families also demanded more information on how calls were made leading up to the chaos that had ensued that day, including information on why a gate near the airport was ordered to remain open, since it was known that the possibility of an attack was high.

“I’m pissed off. I’m very, very angry,” said Mark Schmitz, whose son was killed during the incident. “There’s a lot of pain and it doesn’t get any easier. There’s a hole now that can’t ever be filled.”

Schmitz says he is totally unsatisfied with the information he has gotten so far, and he and other families will continue to push Congress and the Biden administration for more.

In response to Monday’s hearing, a Pentagon spokesperson said, “The Department of Defense expresses our deepest condolences to the Gold Star Families who lost loved ones during the tragic bombing at Abbey Gate. We are forever grateful for their service, sacrifice, and committed efforts during the evacuation operations. We also commend the historic and monumental efforts of all our service men and women who served honorably during the withdrawal period from Afghanistan.”