(CNN) -- People were "thrown to the roof as if they were dolls" and some feared for their lives when a Continental Airlines flight ran into turbulence, shaken passengers said.

Oxygen masks hang from a damaged part of the plane Monday, in a photo by passenger Camila Machado.

The turbulence struck without warning several hours into Monday's Continental Flight 128 from Rio de Janeiro, Brazil, to Houston, Texas. The pilot diverted the Boeing 767-200 to Miami, Florida, to get treatment for the injured.

Continental said seven passengers were transported to hospitals, and about 28 other passengers were treated at the scene. Lt. Elkin Sierra of the Miami-Dade Fire Department said 26 passengers were injured, including four seriously.

"The airplane came down very sharply, and all of us bumped our heads against the ceiling -- twice," Brazilian passenger Celi Dfaria told CNN affiliate WSVN-TV at Miami-Dade International Airport.

"It dropped so hard that everything in the seat-back pockets just flew up in the air. I caught my phone in my lap," passenger Richard Sharp told the Houston Chronicle. Watch what happens when a plane drops »

"The second one was the devastating one. That's when the plane really fell," Fabio Ottolini of Houston, who with his wife and daughter was returning from a visit with family in Brazil, told affiliate KTRK-TV in Houston. "While it was doing that, I saw people being thrown to the roof as if they were dolls."

Don't Miss 26 hurt when plane hits turbulence

Aloiso Dias thought the plane dropped more than twice.

"I felt like I was on a roller coaster," he told WSVN-TV. "I couldn't even see what happened with my wife. I was just holding onto the front of the seat and going with the flow."

He couldn't see because the cabin lights had gone out and "it was pitch black outside," Frederick Bright told the Houston Chronicle.

"I went up, and it was like I was in the air for a minute. Then I came down and I hit my back on the armrest, then I fell into the chair," he said. "I thought I was going to die because the lights went off completely, and all I could see was the red lights" on the wings.

Most of those who were injured had not been wearing seat belts, passengers said.

"It was like in the movies -- anybody who didn't have a seat belt on came right out of their chairs," Manuel Alfaro of Houston told the Chronicle. "It smacked everyone around."

Several people hit the ceiling hard, witnesses said.

"People that weren't seatbelted in flew up and hit the ceiling, so their heads and their faces hit the plastics all up at the top," John Norwood of Houston told WSVN-TV. "A couple of people were badly hurt from the plastic breaking on their faces from the lights. There were people cut, bleeding. There were a few people unconscious." Watch passengers describe the terror »

Deanna Buckley of Houston hit the ceiling but wasn't hurt.

"I hit my head on the light above and it broke the light out and I was showered in glass," she told WSVN-TV. "I was lucky, though. There were people on there whose faces were cut up. It was terrible."

The turbulence came suddenly, catching many passengers asleep.

"It seemed like the back of the plane got it the worst, though, probably because there's more people in the back and a lot of people didn't have their seat belts on," Sharp told the Chronicle.

"You had a lot of people sleeping across the empty rows, so those people were bouncing around on the armrests. They really took the brunt of the beating in the back." Learn more about turbulence and what causes it »

One of those was 13-year-old Thiago Candido, who was traveling unaccompanied.

"Oh, I was scared man," Candido told KTRK-TV. "I was sleeping and I woke up with my head in the ceiling. I didn't know what was going on.

"I thought the plane was falling, just like a big earthquake, but in the air," he said.

The flight carried 168 passengers and 11 crew members. Continental flew remaining passengers to Houston later Monday.

"I think the most important thing about this whole episode is seat belts, all the time," Ottolini told KTRK-TV. "Because we have no way to predict what happened. It just happened."

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