One passenger was killed and 30 injured after a Singapore Airlines flight from London hit severe turbulence en route on Tuesday, forcing it to make an emergency landing in Bangkok, officials and the airline said.

“Singapore Airlines offers its deepest condolences to the family of the deceased. We deeply apologise for the traumatic experience that our passengers and crew members suffered on this flight,” the airline said, adding it was working with Thai authorities to provide all necessary assistance.

The flight fell into an air pocket while the cabin crew was serving breakfast before it encountered turbulence, prompting the pilots to request an emergency landing, Suvarnabhumi airport general manager Kittipong Kittikachorn told a press conference.

A 73-year-old British man died during the incident, likely because of a heart attack, he said. Seven people were critically injured with head injuries. Eighteen people have been hospitalised and 12 are being treated in hospitals, Singapore Airlines said.

It was not immediately possible to reconstruct the incident from publicly available tracking data, but a spokesperson for FlightRadar 24 said it was analysing data at around 07:49 GMT which shows the plane tilting upwards and returning to its cruising altitude over the space of a minute.

A passenger who was on the flight told Reuters that the incident involved the sensation of rising and then falling.

“Suddenly the aircraft started tilting up and there was shaking so I started bracing for what was happening, and very suddenly there was a very dramatic drop so everyone seated and not wearing a seatbelt was launched immediately into the ceiling,” Dzafran Azmir, a 28-year-old student on board the flight said.

“Some people hit their heads on the baggage cabins overhead and dented it, they hit the places where lights and masks are and broke straight through it,” he said.

Kittikachorn said most of the passengers he had spoken to had been wearing their seatbelts.

The spokesperson for FlightRadar 24 said with regard to data showing a drop in height, “Our initial thinking is the turbulence event is prior to the standard descent from 37,000 to 31,000 feet.

That appears to just be a flight level change in preparation for landing.”

The Boeing 777-300ER plane with 211 passengers and 18 crew was headed to Singapore when it made the emergency landing, the airline said.

Singapore news outlet CNA carried blurry pictures supplied by readers that it said appeared to be from the flight. They showed anxious passengers clinging to seats, with oxygen masks hanging from above, personal items strewn across the aisle and rubbish spilt on the floor of the cabin crew area.

Suvarnabhumi airport said the plane requested an emergency landing at 3:35pm local time and landed at 3:51.

3 Indians on flight

There were at least three Indian nationals aboard the Singapore Airlines flight.

Singapore’s new Prime Minister Lawrence Wong extended his condolences to “family members and loved ones of the deceased”.