A flight from Brazil to Texas dropped without warning, throwing flight attendants against the roof.
One passenger said he felt Continental Flight 128 drop without warning while flight attendants were in the aisles, throwing some of them against the roof.
Houston-based Continental said there were 168 people and 11 crew on the Boeing 767. The airline released a statement that said the fasten seat belt sign was illuminated at the time and that about 28 passengers were treated in Miami.
Miami-Dade Fire Rescue spokesman Elkin Sierra said four people were seriously injured aboard the Boeing 767 and another 22 were in stable condition with bumps and bruises. A total of 13 people were taken to hospitals.
The plane was on a night flight from Rio de Janeiro to Houston. Federal Aviation Administration spokeswoman Kathleen Bergen said the turbulence struck about halfway between Puerto Rico and Grand Turk island, north of the Dominican Republic.
The plane reported hitting severe turbulence at 4:30 a.m. (0830 GMT) and landed safely about an hour later at Miami International Airport, Bergen said.
Passenger Fabio Ottolini of Houston said it was about 6 hours into the flight when he felt the aircraft suddenly drop. "People didn't have time to do anything," he said.
Ottolini said flight attendents were serving items in the aisles when the turbulence hit. He said some flight attendenats were thrown against the roof of the cabin and may have been among those injured.
Rio was also the departure airport for Air France Flight 447 that crashed in the mid-Atlantic, more than 900 miles (1,448 kilometers) off Brazil's northeastern coast, in thunderstorms on June 1, killing all 228 people on board.
The FAA's Bergen cautioned against drawing any parallels and said the cause and severity of the turbulence in the Continental case was still being investigated.
"I wouldn't draw any conclusions and comparisons," Bergen said.
Airport officials say some passengers were going on to Houston on various Continental flights about midday. He did not know when the remaining passengers would be expected to arrive in Houston.Reuse content