Police said the attacks may be related but they aren't yet sure.
Two to four young white males were involved, police said. Officials released the surveillance video from Florida Atlantic University showing two men beating one of the victims with what appear to be bats.
The incidents came as the Washington-based National Coalition for the Homeless designated another city in Florida, Sarasota, the meanest city in the nation toward the homeless.
Sarasota bans sleeping outside overnight without permission on public or private property. A judge recently upheld the ordinance passed by city commissioners in August after two similar no-camping rules were declared unconstitutional.
Norris Gaynor, 45, died from his injuries, and the other two men were in serious condition at Broward General Medical Center, according to police. The survivors were not identified.
"I know that there was no confrontation prior to the incident," said Detective Kathy Collins. "They seem to just come out and started beating them immediately."
One of the assaults occurred near the Broward Center for Performing Arts and the other was near a church.
"It's horrifying and most of these guys that are down here are harmless. I mean, really, they are nice guys," city resident Mariane Kroustasis told CBS station WFOR.
Collins said police are asking other homeless if there have been other incidents.