The man, identified as John Meier Jr., 48, of Parkland, Fla., had been running in and out of traffic wearing only a pair of shorts, Broward County Sheriff's Office spokesman Jim Leljedal said.
When Meier violently resisted arrest, a sheriff's deputy pressed the electroshock device directly to Meier's body, Leljedal said. The gun sent an electrical current into Meier that manufacturer Taser International Inc. calls "neuromuscular incapacitation."
Leljedal told The Miami Herald he could not say how many times or how long Meier was Tased.
Meier was pronounced dead at 1 a.m. Wednesday.
A Broward County Medical Examiner's Office investigator would not discuss Meier's autopsy, the Herald said.
Cocaine toxicity or "excited delirium" appears to have caused his death, although toxicology tests have not been finalized, Leljedal said.
Excited delirium is a term critics decry as a "dubious disorder" to mask what they consider police brutality or to explain deaths of people in police custody.
Leljedal told the newspaper the deputy was justified in using the stun gun.
"One deputy tried to get him out of traffic and off the road, but he fought him," Leljedal said. "At that point, he had to find some sort of tool to manage him, and the most appropriate tool was the Taser."