Flight 1780, which was bound for Miami from Aruba, hit the rough air about a half hour before landing on Tuesday. Passengers on the Boeing 757 say it was a very scary experience.
The turbulence was so severe that witnesses say it sent some passengers flying out of their seats.
A spokesperson said there was nothing to indicate the ride would be that rough. American Airlines sent a statement to ABC News saying, "The seatbelt sign was on at the time and nothing on the radar indicated that turbulence was in the area."
Twelve people were hurt in the incident. Five were injured and sent to an area hospital, including two crew members.
ABC News and the Associated Press contributed to this report.