A United States military investigation into a deadly Kabul drone strike on a vehicle in August has found it killed 10 civilians and the driver and that the vehicle targeted was likely not a threat associated with ISIS-K, announced Gen. Frank McKenzie, the top general of US Central Command, at the Pentagon on Friday. McKenzie told reporters that the strike – which he said killed seven children – was a “mistake” and offered an apology. “This strike was taken in the earnest belief that it would prevent an imminent threat to our forces and the evacuees at the airport, but it was a mistake and I offer my sincere apology,” he said. McKenzie added that he is “fully responsible for this strike and this tragic outcome.” The Pentagon’s announcement will likely fuel more criticism of the Biden administration’s chaotic evacuation of Kabul and handling of the withdrawal from Afghanistan more broadly. While McKenzie stressed Friday that future strikes will likely be held to a higher standard, confirmation of the civilian death toll also provides insight into the obstacles ahead for military and intelligence officials tasked with fulfilling President Joe Biden’s promise to make the terror group “pay” for its deadly suicide attack in Kabul. The Pentagon had maintained that at least one ISIS-K facilitator and three civilians were killed in what Chairman of the Joint Chiefs Gen. Mark Milley had previously called a “righteous strike” on the compound on August 29. The investigation released Friday found that all of those killed in the residential compound were civilians. In the lead up to the strike, drone operators surveilled the courtyard for up to 4 to 5 minutes. In that time, a male driver left the vehicle. One child was parking the vehicle and other children were present in the car and the courtyard – as CNN had been told by the Ahmadi family. The military based the strike on a reasonable certainty standard to launch the strike on the vehicle. Tragically, it was the wrong vehicle, a US military official familiar with the investigation told CNN earlier Friday, adding that reasonable certainty is not 100% certainty. “We didn’t take the strike because we thought we were wrong – we took the strike because we thought we had a good target,” McKenzie said. While he acknowledged that the strike “was a terrible mistake,” he said he would “not qualify the entire operation” as a failure. Asked by a reporter to explain how the “complete and utter failure” could have occurred, McKenzie said, “While I agree that this strike certainly did not come up to our standards and I profoundly regret it, I would not qualify the entire operation in those terms.” Previously, US Central Command pointed to “significant secondary explosions” as evidence of a “substantial amount of explosive material” in the vehicle. On Friday, the US military source said that after reviewing footage from infra-red sensors, they would no longer characterize this as an explosion – instead, it was more of a flare up. The US official said that in the time leading up to the strike, the US had at least 60 different intelligence reports about threat streams toward US forces at Hamid Karzai International Airport. A US official with direct knowledge of the standards for a strike of this nature told CNN earlier this month that 10 civilian deaths is an “astronomically high” number and the military would have conducted collateral damage estimates beforehand, meaning commanders were aware that there was a potential for civilian casualties. “Had we cooperation with any local partner, we would have never fired a missile at the vehicle but tried to get to the drivers before they got in the car,” one former intelligence official with knowledge of how these strikes are carried out previously told CNN. “That assumes we had intel on the car as opposed to the people, and maybe after it was already in route, which leaves far fewer options.” Response to the findings Biden was briefed on the details of the investigation on Friday morning, an official said. In a speech last month, the President hailed the strike as an example of the US ability to target ISIS-K. The White House has not yet commented on the investigation’s findings. On Friday, Milley released a statement on the strike calling it “a horrible tragedy.” “In a dynamic high-threat environment, the commanders on the ground had appropriate authority and had reasonable certainty that the target was valid, but after deeper post-strike analysis, our conclusion is that innocent civilians were killed,” Milley said in a statement. “This is a horrible tragedy of war and its [sic] heart wrenching and we are committed to being fully transparent about this incident,” he added. Secretary of Defense Lloyd Austin also apologized for the strike in a statement on Friday, and offered condolences to the family of Zamarai Ahmadi, the driver of the car targeted in the strike. “We now know that there was no connection between Mr. Ahmadi and ISIS-Khorasan, that his activities on that day were completely harmless and not at all related to the imminent threat we believed we faced, and that Mr. Ahmadi was just as innocent a victim as were the others tragically killed,” he said. Austin said he is directing a “thorough review” of the investigation conducted by Central Command and the information that led the US military to conduct it. Austin said the military, when it has reason to believe it has taken innocent life, “investigate it and, if true, we admit it.” “But we also must work just as hard to prevent recurrence – no matter the circumstances, the intelligence stream or the operational pressures under which we labor,” he added. “We will do that in this case.” Human rights group, Amnesty International said Friday’s admission was an an “important step toward accountability” but added that Washington needs to take more steps, including paying reparations to family members and survivors of the strike. “The US must now commit to a full, transparent, and impartial investigation into this incident. Anyone suspected of criminal responsibility should be prosecuted in a fair trial,” said Brian Castner, a senior crisis adviser with Amnesty International’s Crisis Response Program. House Intelligence Chairman Adam Schiff said in a statement Friday that “after such a devastating failure - one that, by the Department’s estimate, killed 10 civilians, at least 7 of them children - it cannot be the last step.” “We need to know what went wrong in the hours and minutes leading up to the strike to prevent similar tragedies in the future,” the California Democrat said, adding that his committee “will continue to press for answers.” This story has been updated with further developments.