Leach, 61, was taken to the University of Mississippi Medical Center in Jackson, about 125 miles away from his home in Starkville, following “a personal health issue.”
“Mike Leach needs a miracle, folks,” Robbie Faulk, a 247 Sports reporter who covers MSU, tweeted. “Continue to pray.”
MSU said in a statement it had no comment on Leach’s condition, except to say “that the thoughts and prayers of the university are with Mike and (wife) Sharon and their family.”
Coaches and athletic personnel from around the country shared their support.
“Prayers for Coach Leach and family. We’re all on the same team tonight,” Mississippi athletic director Keith Carter wrote on Twitter.
University of Houston head football coach Dana Holgorsen also tweeted: “My thoughts are with my mentor, my colleague and, more importantly, my friend, Mike Leach.”
“While I am devastated by today’s news, I know Mike is a fighter with an incredible spirit and I know he will continue to battle,” Holgorsen continued. “Prayers to Sharon and their extended family.”
USC’s Lincoln Riley also called on others to pray for Leach.
“Prayers for my good friend Mike Leach,” Riley posted. “Please keep Coach and his family in your prayers.”
MSU said Defensive Coordinator Zach Arnett would be placed in charge of its football team until Coach Leach returns.