The Singapore-bound Boeing 777-300ER, which took off from London, was diverted to Bangkok after the incident.

211 passengers and 18 crew were on board, the airline said in a statement.

“Singapore Airlines offers its deepest condolences to the family of the deceased,” the statement said.

“Our priority is to provide all possible assistance to all passengers and crew on board the aircraft.”

The airline said it was working with Thai authorities to provide medical assistance to passengers.

Thai authorities have dispatched ambulances and emergency teams to Suvarnabhumi Airport.

“I am deeply saddened to learn about the incident on-board Singapore Airlines flight SQ321 from London Heathrow to Singapore,”

Singapore’s Transport Minister Chee Hong Tat said in a Facebook post following the incident.

One passenger told Reuters the aircraft had begun “tilting up and there was shaking”.

“So I started bracing for what was happening, and very suddenly there was a very dramatic drop,” 28-year-old Dzafran Azmir said.

“So everyone seated and not wearing seatbelt was launched immediately into the ceiling.

“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.”

Tracking data provided by FlightRadar24 showed the flight was cruising at 37,000 feet before suddenly dropping to 31,000 feet in just three minutes.

The aircraft remained at 31,000 ft for approximately 10 minutes before landing in Bangkok 30 minutes later.

“There’s some suggestion the flight hit an air pocket before it had to make this emergency landing,” Sky Asia journalist Cordelia Lynch said.

“There are some images circulating on social media that show parts of the plane inside and a lot of scattered debris.”

More to come.