(CNN) -- Travelers looking for a relaxing trip to Orlando got off to a terrifying start Sunday when their flight suddenly dropped in turbulence, injuring several passengers.
There were 265 people on board, including a crew of 10, when US Airways Flight 735, an Airbus A330, hit turbulence about 17,000 feet over Delaware.
"Everybody kind of let out a collective 'holy crap,' " passenger Mark Pensiero told CNN's "New Day" on Monday.
It "probably lasted no more than four or five seconds," he said. But as any flier can imagine, a few seconds of that can feel much longer.
It felt like "going down the bottom of a roller coaster," passenger Jake Levin told CNN affiliate WKMG after the flight arrived about five hours late in Orlando.
"You saw ... shoes and apples and all kinds of things (flying in the air). It was so quick," he said. "They weren't sure if we were dropping for good or what was happening."
"I thought we were going down," said Victoria Raines, Levin's girlfriend.
Six people were injured in the incident after takeoff from Philadelphia International Airport on Sunday afternoon, US Airways said.
Five people, including two flight attendants, were taken to hospitals for treatment after the plane returned to Philadelphia, said spokesman Bill McGlashen. The sixth didn't need hospitalization.
Pensiero told CNN he was surprised to hear that anyone was injured. "I don't know who would have had their seat belt off," he said. "We were not in smooth air at any time."
Other passengers he spoke with described a woman hitting the top of the aircraft, her feet up at their eye level, Pensiero said.
Soon after the incident, the crew asked any medical personnel on board to hit their call lights, Pensiero said.
There had been some reports of light turbulence in the area, but nothing as severe as what the plane ran into.
The Federal Aviation Administration will investigate.
In a separate incident, the wing of a WestJet 737 clipped the horizontal stabilizer of a JetBlue plane while on the ground at Orlando International Airport. The horizontal stabilizer is a lifting surface on a plane's tail.
The WestJet flight was pushing back from the gate when the incident happened, according to the FAA.