A 1-year-old boy died on Thursday at a hospital and family members were being questioned about the incident.
NBC 6 video showed a man in handcuffs at Kendall Regional Hospital, but his relationship to the child wasn't immediately known.
The Miami-Dade Police Department Homicide Bureau was investigating the matter.
Police said the child, who was unresponsive, had been transferred Kendall Regional Hospital from a house at 1071 SW 151 Place in west Miami-Dade County. Police were at the address Thursday night.
No further information was immediately released.
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