When Miami police and rescue crews arrived at a club called The Spot around 1 am, they said they found chaos among the large crowd of adults and teenagers gathered there. Rescuers found wounded people inside and outside the club, reporting some were too hurt to flee.
At least one person was reported in critical condition but the extent of the other injuries wasn't immediately known. At least three of the victims were transferred to a paediatric unit.
One male was found unresponsive and not breathing when emergency responders arrived. Five girls between 11 and 17 years old also suffered gunshot wounds, Carroll said.
Details were sparse in the hours after the shooting as investigators were seeking to piece together what happened.
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"The investigators are still interviewing witnesses. They're going from hospital to hospital," police spokeswoman Frederica Burden told AP.
She said it was not immediately clear how many shooters there were and what prompted the gunfire.
Fire Rescue officials will follow-up with the club to see whether it's a teen club, whether it's licensed as a club for regular gatherings or whether this was an informal gathering, Carroll said.