• One passenger died and 30 others were injured onboard the London to Singapore flight on Tuesday, which encountered "sudden extreme turbulence" about 10 hours after departing from Heathrow Airport.
• A relief flight carrying "131 passengers and 12 crew members who were on board SQ321 arrived in Singapore" at 5:05 a.m. local time on Wednesday, the airline said in a Facebook update.
• "I would like to express my deepest condolences to the family and loved ones of the deceased passenger. We also deeply apologise for the trauma experienced by all passengers and crew members on this flight," Singapore Airlines' CEO Goh Choon Phong said.

SINGAPORE — More than 140 passengers and crew that were on the Singapore Airlines flight that made an emergency landing in Bangkok Tuesday after encountering severe turbulence arrived safely in Singapore early on Wednesday.

One passenger died and 30 others were injured onboard the London to Singapore flight on Tuesday, which encountered "sudden extreme turbulence" about 10 hours after departing from Heathrow Airport.

A relief flight carrying "131 passengers and 12 crew members who were on board SQ321 arrived in Singapore" at 5:05 a.m. local time on Wednesday, the airline said in a Facebook update.

The Boeing 777-300ER, which was carrying carrying 211 passengers and 18 crew, was flying over the Irrawaddy Basin at an altitude of 37,000 feet when it experienced sudden turbulence.

A 73-year-old British national died of a suspected heart attack during the incident. At least 30 people were injured, with 18 of them hospitalized and 12 being treated in hospitals, the airline said.

"I would like to express my deepest condolences to the family and loved ones of the deceased passenger. We also deeply apologise for the trauma experienced by all passengers and crew members on this flight," Singapore Airlines' CEO Goh Choon Phong, said in a video message posted on Facebook.

The pilot declared a medical emergency and diverted the plane to Bangkok, and the plane arrived at the Thai capital at 3:45 p.m. Bangkok time.

As of early Wednesday morning, another 79 passengers and six crew members from the SQ321 flight remained in Bangkok, the airline said. They include people receiving medical care, as well as family members and loved ones of those on the flight.

More than a quarter of the passengers on flight SQ321 were from Australia, 47 were from the United Kingdom and 41 from Singapore, SIA said in an update. Other passengers were from New Zealand, Malaysia and others.

SIA is fully cooperating with the relevant authorities in the investigation into this incident, the airline said. The Singapore stock market was closed for the Vesak Day holiday on Wednesday.

Boeing said it was in touch with SIA about the incident and was ready to offer support. Singapore received the aircraft in 2008, according to Flightradar24.

The Aviation Safety Network has recorded seven incidents for Singapore Airlines, last logging accident fatalities for one of the company's flights in October 2000, when 83 people were killed when the plane crashed into construction equipment at Taipei's main airport.

— CNBC's Sophie Kiderlin and Leslie Josephs contributed to the report.

Correction: An earlier version of this story misstated the day that the emergency landing occurred.