(CNN) -- Oklahoma State University women's basketball coach Kurt Budke and assistant coach Miranda Serna were killed when their plane crashed on the way to a recruiting trip in Arkansas, university officials said Friday.
Former Oklahoma state Sen. Olin Branstetter and his wife, Paula, also died in the crash Thursday, university spokesman Gary Schutt said.
"It's a terribly sad day," he said.
The crash occurred in Perry County, Arkansas, leaving no survivors.
The plane, a Piper Cherokee PA-28, according to FAA records, crashed under "unknown circumstances" in a wooded area about four miles south of Perryville, Arkansas, about 4:30 p.m. CT on Thursday, agency spokesman Lynn Lunsford said Friday.
No additional information about the crash was immediately available.
The National Transportation Safety Board has sent investigators to the crash site, the agency said Friday.
Budke and Serna were on a recruiting trip to Little Rock, Arkansas, the university said.
"For any coaching community to lose bright stars like Kurt and Miranda is tragic," NCAA President Mark Emmert said in a statement. "This is a profound loss for the Oklahoma State women's basketball family, the entire university and future women's basketball players as well."
University officials credited Budke for turning the school's women's basketball program around, culminating with a top-10 national ranking and an appearance in the second round of the NCAA tournament last season. He was in his seventh season with the school.
"Kurt was an exemplary leader and a man of character who had a profound impact on his student-athletes," Oklahoma State President Burns Hargis said. "He was an outstanding coach and a wonderful person. We send our deepest sympathies to his wife, Shelley, and their children, Sara, Alex and Brett."
Serna was also in her seventh season with OSU after coming to the school to work for Budke from Louisana Tech, where they both previously worked. She served as the program's recruiting coordinator, according to the school.
Hargis called her "an up-and-coming coach and an outstanding role model for our young ladies."
"Its our worst nightmare," he added.
The school called off games scheduled for Saturday and Sunday, and grief counselors were on hand for athletes and staff, the university said.
Jim Littell, the team's associate head coach, will take over as interim head coach, according to Mike Holder, OSU vice president for athletics.
The crash is the second fatal plane crash to strike the OSU basketball program in nearly 11 years.
Ten people, eight of them associated with the university's men's basketball program, died when their plane crashed in a Colorado snowstorm on January 28, 2001.