MIAMI — Some passengers were snoozing while others snacked when the first turbulence rattled Continental Flight 128 over the Atlantic. Suddenly, the jetliner began to plunge and shake violently, hurling passengers over seatbacks and slamming them against luggage bins.

The Boeing 767 made an emergency landing in Miami early Monday so at least 26 injured, four seriously, could receive medical help. But the sudden turbulence that rocked the overnight flight from Rio de Janeiro was an all-too-real reminder of an Air France flight — also traveling from Rio — that crashed into the mid-Atlantic in June during thunderstorms, killing all 228 people on board.

Said 20-year-old passenger Camila Machado, who was going to Las Vegas and was treated for a bruised cheek: “I felt like the airplane was going to crash. I felt like we were going to die. Like, the first thing I thought about was Air France.”

Federal Aviation Administration spokeswoman Kathleen Bergen cautioned against drawing any parallels between the two flights and said the cause and severity of the turbulence in the Continental case was still being investigated.

Meteorologists differed on weather conditions at the time the Houston-bound plane encountered the turbulence just northwest of Puerto Rico.

Henri Agramonte, a forecaster at the Dominican Republic national office of meteorology, said there were thunderstorms early Monday, which were caused by a tropical wave that could have generated strong winds off the country’s northern coast. But Brian Wimer, a meteorologist from the State College, Pa.-based Accuweather, said there were no thunderstorms in the area.

Wimer speculated that the plane may have encountered clear air turbulence, which occur at high altitudes in tranquil and cloudless conditions.

Bergen said it’s premature to say whether clear air turbulence was the cause of the Flight 128 problem. She said the FAA, NASA, and private companies are working to develop turbulence warning technology that could be used in flight.

Aviation officials say air turbulence is rarely more than a nuisance. Still, turbulence was responsible for 22 percent of all U.S. airline accidents and 49 percent of serious-injury accidents between 1996 and 2005, the National Transportation Safety Board reported in an annual safety review in March.

“It was just so sudden you didn’t really have time to react,” said passenger Carolina Portella, 18, describing what happened on Flight 128.

“I grabbed the hand of the person next to me, and just held on,” she said. “I mean it was really frightening.”

Flight attendants in the aisle were thrown against the ceiling. Passengers who weren’t belted in went flying into the overhead compartments; one woman hit a luggage bin so hard that her head stuck there. Oxygen masks dropped.

“One lady, she just came out of her seat and flew over the middle row, hit her head on the wall and landed on her back,” said 13-year-old passenger Diego Saavedra, whose nose was bandaged as he spoke in the terminal of Miami International Airport.

“All of a sudden there were people coming up off their seats, people screaming, little kids crying, people saying please, ow, help please,” Saavedra said.