Tuesday is a somber day in the football world after Mississippi State coach Mike Leach died at 61.

Leach, one of the most candid and lively personalities in sports, died after reportedly suffering a heart attack on Sunday. Mississippi State, where Leach coached for three seasons after stints at Washington State and Texas Tech, said Leach died “following complications from a heart condition.”

“We are heartbroken and devastated by the passing of Mike Leach,” MSU interim athletics director Bracky Brett said in a statement. “College football lost one of its most beloved figures today, but his legacy will last forever. Mike’s energetic personality, influential presence and extraordinary leadership touched millions of athletes, students, coaches, fans, family and friends for decades.”

Texas Tech called Leach “one of the most innovative offensive minds in college football history” in a statement.

“His impact on Texas Tech Football alone will live on in history as one of the greatest tenures in the history of our program,” the school’s statement read. “From his 84 wins to his record-setting offenses, Coach Leach quickly built a legacy here at Texas Tech that will never be forgotten.”

Chiefs star Patrick Mahomes, who played at Texas Tech after Leach’s tenure, wrote on Twitter, “Prayers to the Leach family!🙏🏽🙏🏽 True legend of the game!”

Cowboys QB Dak Prescott, who played at Mississippi State from 2011-15, paid tribute to Leach on his Instagram Story.

“Thank you for your impact on the lives you coach and our university!” Prescott wrote. “Rest easy pirate.”

Former Texas Tech coach and current Arizona Cardinals coach Kliff Kingsbury said in a statement that there’s “no way” he’d be where he is without Leach.

“He was a mentor, a friend and one of the most special people I’ve ever met,” Kingsbury said.

Leach’s former Big 12 rivals, ex-Texas coach Mack Brown and ex-Oklahoma coach Bob Stoops, each offered prayers to Leach’s family on Twitter.