Former Oklahoma head coach and Nebraska defensive line coach John Blake has died, according to a report from Dean Blevins of OKC-KWTV. He was 59 years old.

According to the report, Blake died after suffering a heart attack while on a walk.

“Sad news, John Blake has died. Coach Switzer tells me it was a heart attack while out walking,” Blevins said in a tweet. “Says he’d lost a lot of weight and was doing well. Prayers w the former #Sooners HC and devastated family. RIP.”

Blake played college football at Oklahoma from 1979-82 and jumped into coaching shortly after his playing career. Most of his early career was at Oklahoma, joining the Sooners staff in 1989 as the defensive line coach after a two-year run at Tulsa. He then coached linebackers at OU from 1990-92 before coaching the defensive line with the NFL’s Dallas Cowboys for three seasons.

In 1996, Blake was named the head coach at Oklahoma. He led the Sooners to a 12-22 record in three seasons.

Blake later had a stop at Nebraska, where he served as the defensive line coach for three seasons (2004-06). He also coached at Mississippi State (2003), North Carolina (2007-10) and with the Buffalo Bills (2016).