15 people, mostly teens, shot at Miami nightclub By Ralph Ellis, CNN

(CNN) -- Fifteen people, mostly teenagers, were shot early Sunday morning at a Miami nightclub, Miami police reported.

Police spokeswoman Frederica Burden said the shooting happened about 1 a.m. The victims range in age from 11 to 25, and one person was critically injured, she said.

"At this point, we are not sure if we have one shooter or multiple shooters," she said.

CNN affiliate WPLG said the shooting happened at The Spot nightclub at Northwest 64th Street at Seventh Avenue. A large party was being held when shooting broke out.

Witnesses told police they heard about 100 gunshots, WPLG reported.

With so many wounded people, emergency responders had to treat some victims on the sidewalk. The wounded were taken to Jackson Memorial Hospital.

"It turned out to be a mass casualty incident," said Capt. Ignatius Carroll of Miami Fire Rescue.

Burden didn't know a motive.