One of the four people killed in a hot air balloon crash in the Arizona desert over the weekend texted his longtime girlfriend to tell her “goodbye” in the moments before impact, according to local station KTVU. Chayton Wiescholek, 28, was one of 13 people aboard the balloon on Sunday, according to the Eloy Police Department. Eight people—among them Kinsey Taylor, Wiescholek’s girlfriend—took part in a “planned skydiving event” that went off without a hitch prior to the balloon malfunctioning, police added. Wiescholek’s father, Gary Wiescholek, told KTVU that his son had texted Taylor “on the way down,” writing, “This ain’t gonna be good, I love you, goodbye.” The exact cause of the crash remained under investigation on Wednesday, but officials announced earlier this week that preliminary information appeared to point to an “unspecified problem” with the balloon’s envelope.