Specialist Paramedic Cody Medley, 22, died at Wishard Hospital early Sunday after the Saturday accident, WISH-TV, Indianapolis, reported.
"We grieve with our IEMS family as we learn of the passing of specialist Cody Medley," said Troy Riggs, director of the city of Indianapolis Department of Public Safety. "Please keep his family and his friends in your thoughts and prayers."
Timothy C. McCormick, 24, died Saturday of injuries sustained in the accident, officials said.
Police said the ambulance McCormick and Medley were in was struck by a passenger vehicle while going through an intersection early Saturday.
The ambulance, which had the right of way, was knocked onto its side, officers said.
Officials say the driver of the vehicle, Jade Hammer, 21, smelled of alcohol when officers talked to her after the accident.