Coach Lane Kiffin was visibly shaken as he met with reporters during his regularly scheduled news conference, saying Thomas was "potentially severely injured." The school later said he was doing well and being discharged from the hospital.
"Our physicians will be following up with him in the coming days for further evaluation," Pat Jernigan, Ole Miss assistant athletic director for sports medicine, said in a statement.
Kiffin responded later on social media: "Prayers answered so happy for DaMarcus and his family! Keep praying for his recovery. Great job by Pat and all the people that helped care for him today."
After Kiffin's initial comments, in which he said Thomas "was hit and hasn't moved since," the coach came back to say that Thomas has regained some movement and feeling in his body.
"I don't know what that means exactly," Kiffin said, "but it sure feels like great news compared to what it was."
Kiffin said practice was stopped early.
The coach said he found himself thinking about his own kids as athletic trainers were asking Thomas whether he could feel anything on his body and he said no.
"Hopefully this is some severe stinger," Kiffin said. "I did ask the medical staff and they said that does happen sometimes. So praying somehow that's what it is."
All of the players remained on the field waiting for the helicopter to arrive.
Thomas, 18, is from Whatley, Alabama. He has appeared in five games.
"If you saw what I saw, you wouldn't be worried about whether he was going to play or not," Kiffin said.
Thomas, a three-star prospect, signed with Ole Miss over offers from South Alabama, Southern Miss, Tulane and others.
Ole Miss is coming off a 54-21 win over Vanderbilt on Saturday, improving to 2-4 during Kiffin's first season as coach.