The fire broke out at 17000 NW 67th Ave., Miami-Dade police say.
Three people, a mother and two children, ages 2 and 12, died in the third-floor unit fire at the Country Lane condos, according to early reports.
Neighbors tried to help before firefighters and police arrived at the complex after midnight.
"You just heard people screaming," neighbor Dylan Oliver told CBS4.
Thomas said a family was brought out of the condo "unconscious."
"A tragic incident," Miami-Dade police spokesman Alvarado Zabaleta told the Miami Herald on the scene.
The fire started in the kitchen and three people were found in the bedroom, he said. Their deaths are possibly due to smoke inhalation, he said.
The mother was identified as Katrina Williams, 42.
The father was at work at the time, police said.
This bulletin will be updated as more information becomes available.
Miami Herald photojournalist Walter Michot contributed to this report.