The testimony provides an important perspective on what the US military knew as it drew conclusions that no Afghans or US personnel were shot. Their conclusions have stated that Marines did not come under fire in the aftermath, and only shot controlled bursts of fire at two suspicious military-aged males, which hurt no one.

However, in the documents, several Marines recall gunfire impacting around them in the aftermath of the blast, one seeing a round hit a window in front of him. They raise questions as to whether all the rounds fired have been accounted for by investigators, or whether they were all harmless warning shots.

One Marine from 1st Regiment recalled in an interview on October 1 what he saw when he ran into the tower next to the Abbey Gate entrance to the airport where an ISIS bomber detonated his device. "I saw Marines return fire. I heard three distinct shots hit the back windows of the tower. The third round impacted right in front of my face as I was closing the ballistic glass window."

Another said: "I could hear sporadic rounds snapping overhead for about 5 minutes. I didn't see any tracers but saw sparks when bullets would impact things."

A group interview by investigators with junior Marines who were at the blast site, from G company 2/1 Marines, had many accounts of bullets impacting around the troops. One Marine said: "While I was applying tournequets (sic.) I saw ricochets. Never saw a shooter."

Another quote reads: "I saw the shots hitting around us". Another reads: "I saw ricochets but didn't hear gunfire."

In other excerpts, Marines suggested colleagues fired many shots back. It is unclear how many Marines were interviewed, as names of speakers are redacted.

"If there were only 2-3 shooters and the amount of our guys shooting back, they would've been done," said one. Another said: "I heard that a recon guy dumped about three magazines of ammo that way."

In some interviews, other troops say they did not fire at all in the aftermath, despite the chaos and possibility they were under further attack. Much of the testimony is consistent with the conclusions of investigators.

But the testimony also raises questions as to how thoroughly the US military assessed whether patients their medics treated after the blast were shot. US investigators have stated that medics treating the injured initially mistook injuries caused by ball bearings as gunshot wounds, as they looked so similar.

One medic said: "I think there may have been GSWs [gunshot wounds] sprinkled in, but that's inconclusive and wasn't medically worth trying to figure out. They would be treated the same." The US military investigation has insisted there were no gunshot wounds detected among any patients US medics treated on the airport, and no bullets were recovered.

One US medic, identified as a "68Z," the military designation for a senior officer often with medical experience, said: "Originally, a lot of the wound (sic.) were classified as gunshot wounds, but they were actually because of shrapnel. But there were some gunshot wounds. There was a non-US patient that had a bullet inside the back of his head after small arms fire." The medic, whose name is redacted, said in the interview they saw 70 patients and: "I was the person writing the patients on the board and assisting everywhere."

Captain Bill Urban, a spokesman for US Central Command, said in an email earlier this week to CNN that the medic was contradicted by surgeons in the operating theater who said they did not remove bullets as they worked. He said the 68Z officer was "was not a Medical Doctor or Officer, and was not administering medical care in the Operating Room". The "68Z" does however, in the interview, say they were formerly a "combat medic" and an "LPN," a licensed practical nurse.

Urban said some of the testimony highlighted to him by CNN were "examples of statements deemed less credible ... For each of these instances you describe, we had contradictory information from several credible sources."

Urban added: "While there are conflicting statements, as well as inconsistent evidence, the investigation team drew its conclusions based on a preponderance of all the evidence collected, after careful analysis and synthesis."

Urban also pointed to the likely impact of the blast on troops' recollections, and noted how investigators "assessed credibility of Service Members based on their maturity and experience in operational environments." The documents appear to record mostly the junior Marines at the scene of the blast seeing rounds impacting around them.

Urban added that medics at the airport providing care did not assess how patients were injured. "Medical providers did not make forensic findings at HKIA and were solely focused on treatment," he wrote in the email.

"Many individuals and Leaders unaffected by the blast indicated that claims of incoming rounds were not accurate", Urban said.

Investigators during Friday's briefing at the Pentagon said the "confined space" in which the warning shots were fired "caused an echo which created the illusion of a firefight". Urban added: "We have multiple sources unaffected by the blast that indicate those affected by the blast who claimed to fire their weapons did not."