More details about the plane crash that killed NASCAR driver Greg Biffle and his family have emerged amid an investigation by the National Transportation Safety Board, but officials remain unsure of who was flying the plane. "At this time, we have been unable to verify who was flying the airplane," NTSB board member Michael Graham said in a press conference held Friday, December 19. "We do know three of the occupants did possess a pilots' license but we have been unable to verify this at this time. That is one of the things we're working on." Graham did not name the individuals with pilots licenses, but Biffle, 55, and Dennis Dutton, who was also on board, were both pilots. News broke on Thursday, December 18, that a Cessna C550 plane belonging to Biffle crashed and burst into flames shortly after takeoff at the Statesville Regional Airport in North Carolina. The business jet was supposed to fly to Sarasota, Florida, before taking off on a second leg to the Bahamas. The aircraft was then scheduled to fly to Fort Lauderdale before returning to North Carolina. "At approximately 10:15 am, an aircraft crashed while landing," airport officials told The Charlotte Observer in a statement. "Federal Aviation Administration (FAA) is en route and will investigate the incident." NASCAR Driver Greg Biffle's Fatal Plane Crash: Everything We Know So Far A close friend of Biffle's later took to social media to reveal that the race car driver, along with his wife, Cristina Grossu, and his two kids, were on the plane when it crashed. "Unfortunately, I can confirm Greg Biffle, his wife Cristina, daughter Emma and son Ryder were on that plane ... because they were on their way to spend the afternoon with us," Garrett Mitchell wrote via Facebook. "We are devastated. I'm so sorry to share this." North Carolina Congressman Richard Hudson, another friend of Biffle's, confirmed the deaths of the athlete and his family members. James Gilbert/Getty Images "I am devastated by the loss of Greg, Cristina, and their children, and my heart is with all who loved them," he wrote via X. "They were friends who lived their lives focused on helping others. Greg was a great NASCAR champion who thrilled millions of fans. But he was an extraordinary person as well, and will be remembered for his service to others as much as for his fearlessness on the track." Three other people were killed in the crash, a statement from the families of the deceased confirmed on Thursday. "We are devastated by the loss of our loved ones. This tragedy has left all of our families heartbroken beyond words," the statement, shared by FOX Sports reporter Bob Pockrass via X, read. "Greg and Cristina were devoted parents and active philanthropists whose lives were centered around their young son Ryder and Greg's daughter Emma (mother - Nicole Lunders). Emma was a wonderful human being with a kind soul who was loved by many people. Ryder was an active, curious and infinitely joyful child." Who Was Greg Biffle? What to Know About the NASCAR Legend Whose Plane Crashed The statement continued, "Dennis Dutton and his son Jack were deeply loved as well, and their loss is felt by all who knew them. Craig Wadsworth was beloved by many in the NASCAR community and will be missed by those who knew him." The post concluded, "Each of them meant everything to us, and their absence leaves an immeasurable void in our lives. We ask for privacy, compassion and understanding as we grieve and begin to process this unimaginable loss. We are grateful for the kindness and support that has been extended to our families during this incredibly difficult time. At this moment, our focus is on honoring their lives and supporting one another." Biffle was a highly-decorated NASCAR driver with more than 50 wins throughout his career. He was named one of the 75 best NASCAR drivers in history in 2023.