A U.S. military refueling aircraft crash in Iraq killed six service members, U.S. officials said Friday, including an Alabama father who had been deployed less than a week before the incident. The crash occurred on Thursday, and U.S. Central Command said it happened in “friendly” airspace while supporting operations against Iran.

Alex Klinner, 33, was among those killed, his brother-in-law, James Harrill, said while confirming Klinner’s death. Harrill said Klinner was deployed less than a week when the refueling aircraft he was aboard crashed. Harrill said Klinner leaves behind three children: 7-month-old twins and a 2-year-old son.

Harrill described Klinner as a devoted parent, saying, “It’s kind of heartbreaking to say: He was just a really good dad and really loved his family a lot — like a lot.” Harrill said he last saw Klinner in January, when Klinner shoveled Harrill’s vehicle out of snow during a family wedding, and he helped set up a GoFundMe for Klinner’s family.

The U.S. government said the three people killed who were assigned to the 6th Air Refueling Wing at MacDill Air Force Base in Florida included Klinner, along with Capt. Ariana Savino and Tech. Sgt. Ashley Pruitt. Alabama Gov. Kay Ivey said Klinner was stationed in Birmingham, and the government identified Savino and Pruitt as from Covington, Washington, and Bardstown, Kentucky, respectively. Officials later identified the remaining three service members as assigned to the 121st Air Refueling Wing at Rickenbacker Air National Guard Base in Columbus, Ohio.

U.S. and state officials identified the three Ohio-assigned service members as Capt. Seth Koval, Capt. Curtis Angst and Tech. Sgt. Tyler Simmons. The article reported that the U.S. government listed Koval from Mooresville, Indiana, while the Ohio National Guard listed his home as Stoutsville, Ohio. The Ohio National Guard listed both Angst and Simmons from Columbus, Ohio, while the U.S. government listed Angst as being from Wilmington, Ohio.

U.S. Central Command said the crash occurred after an unspecified incident involving another aircraft, and that the other plane landed safely, according to U.S. military officials. The officials said the investigation is ongoing and that the crash was “not due to hostile or friendly fire.”

Family members described Klinner in posts and statements after the death. Klinner’s wife, Libby Klinner, posted condolences and wrote that their children “won’t get to see firsthand the way he would jump up to help in any way he could,” and also wrote, “They won’t get to feel the deep love he had for them.” Harrill said Klinner had “this steady command about him” and was “literally one of the most kindest, giving people.”

The article said Simmons was a boom operator responsible for transferring fuel from the tanker to the receiving aircraft, based on his Air Force biography. Simmons’ mother, Cheryl Simmons, said she was making funeral plans for her son. In a statement obtained by WCMH-TV in Columbus, Simmons’ family said they were “saddened beyond measure” to hear about the crash, and described his “smile” and the family’s grief.

Military officials said the refueling aircraft was a KC-135, which is designed to refuel other planes in midair. The article said the aircraft can also be used to transport wounded personnel and conduct surveillance missions, and that the Congressional Research Service said the Air Force had 376 KC-135s last year, including 151 on active duty, 163 in the Air National Guard and 62 in the Air Force Reserve.