SINGAPORE - Passengers and crew aboard a Singapore Airlines flight on May 21 were midway through a routine breakfast service when the plane plunged without warning, throwing things in the cabin, even people, everywhere.

The bout of severe turbulence, which occurred about 10 hours into the flight of SQ321 from London to Singapore, left a scene of chaos in the plane, with dents in the overhead cabin panels, oxygen masks and panels hanging from the ceiling and luggage strewn about.

“I saw people from across the aisle going completely horizontal, hitting the ceiling and landing back down in really awkward positions. People, like, getting massive gashes in the head, concussions,” passenger Dzafran Azmir, 28, told Reuters after arriving in Singapore.

Passengers told reporters they saw heads slamming into the overhead lights - in some cases the impact was forceful enough to dent the panels.

One passenger, who described what happened as the worst day of this life, said things were going “very smoothly” up until the moment of turbulence.

“And suddenly, the plane plunged,” he told the BBC, adding that he had just returned from the restroom and that there was “no warning at all”.

He and his wife ended up hitting their heads on the ceiling, as they witnessed other passengers who were walking around forced into “somersaults”.

The passenger also said that the crew,...