MIAMI—Paramedics at Miami International Airport treated at least six passengers who complained of bumps and bruises from turbulence Friday on an American Airlines flight from Argentina, authorities said.

At least one passenger was transferred on a stretcher, said Miami-Dade County Fire Rescue spokesman Arnold Piedrahita.

Flight 908 was making a descent into the airport before 7 a.m.  when it hit severe turbulence at 30,000 feet, said Tim Smith, a spokesman for Fort Worth, Texas-based American Airlines. The “fasten seat belt” light was on.

Six people—two flight attendants and four passengers—were taken to the hospital with back and neck injuries. Their conditions were not immediately available.

“Flight attendants, at that altitude, would still be up for duty,” Smith said. He could not say if the passengers were walking around the cabin or in their seats.

The Boeing 777 carrying 246 passengers and 14 crew members from Buenos Aires landed safely, Smith said.

American flight attendants were scheduled to picket at the airport Friday morning to protest poor working conditions. That protest was planned before the incident.