A game official told several reporters that a bone snapped. Trainers immediately covered the leg with a towel and placed Ware on a backboard, then lifted him onto a stretcher.
He was taken to nearby Methodist Hospital, according to a statement from tournament officials. Louisville officials said no additional information was immediately available.
The injury occurred with 6:33 left in the first half as Duke's Tyler Thornton made a 3-pointer to get the Blue Devils within 21-20. Ware tried to contest the shot and his leg buckled when he landed, bending gruesomely.
The injury happened in front of the Louisville bench, and the Cardinals were overcome with emotion.
Louisville forward Wayne Blackshear fell to the floor, crying, and Chane Behanan looked as if he was going to be sick on the court, kneeling on his hands and feet. Peyton Siva sat a few feet away, a hand covering his mouth.
Someone finally pulled Behanan to his feet, but he doubled over and needed a few seconds to gather himself. As Ware was being loaded onto a stretcher, the Cardinals gathered at midcourt until coach Rick Pitino called them over, saying that Ware wanted to talk to them before he left.
Pitino wiped away his eyes as Ware was wheeled out, as did several of the Louisville players.
In the immediate aftermath, those who had been watching the game on television took to social media to express their concern. Former Washington Redskins quarterback Joe Theismann, who famously sustained a broken leg during a Monday night football game against the New York Giants, tweeted that, ''Watching Duke/ Louisville my heart goes out to Kevin Ware.''
Louisville, the top overall seed in the tourney, went more than 3 minutes without scoring after the injury but regained its composure to take a 35-32 halftime lead.