Media reports say there were no signs of survivors.

The airline said it deeply mourned the passengers and crew, without specifying how many people had been killed.

Boeing said it was ready to assist China Eastern and was in contact with US transportation safety regulators over the incident.

Chinese media showed brief highway video footage from a vehicle’s dashcam apparently showing a jet diving to the ground behind trees at an angle of about 35 degrees off vertical.

Reuters could not immediately verify the footage.

The plane was en route from the southwestern city of Kunming, capital of Yunnan province, to Guangzhou, capital of Guangdong, bordering Hong Kong, when it crashed.

China Eastern said the cause of the crash, in which the plane descended at 31,000 feet a minute according to flight tracking website FlightRadar24, was under investigation.

The airline said it had provided a hotline for relatives of those on board and sent a working group to the site.

There were no foreigners on the flight, Chinese state television reported, citing China Eastern.

Relatives, friends and colleagues of passengers gathered late on Monday in a cordoned off area at the jet’s destination, Guangzhou Baiyun International Airport.

One man surnamed Yan said that a colleague had been on the plane, and that he had notified the 29-year-old’s mother.

“When she picked up the phone, she choked up,” said Yan, adding that he had a “heavy heart” when he heard the news.

China Eastern staff were making arrangements for relatives who wished to travel to the crash site on Tuesday, Yan said.

Reuters was not able to independently verify Yan’s identity.

The aircraft, with 123 passengers and nine crew on board, lost contact over the city of Wuzhou, China’s Civil Aviation Administration of China (CAAC) and the airline said.

Media cited a rescue official as saying the plane had disintegrated and caused a fire destroying bamboo trees.

The People’s Daily quoted a provincial firefighting department official as saying there was no sign of life among the debris.

State media showed a piece of the plane on a scarred, earthen hillside. There was no sign of a fire or personal belongings.

Crashes during the cruise phase of flights are relatively rare even though this phase accounts for the majority of flight time.

Boeing said last year only 13 per cent of fatal commercial accidents globally between 2011 and 2020 occurred during the cruise phase, whereas 28 per cent occurred on final approach and 26 per cent on landing.

“Usually the plane is on auto-pilot during cruise stage. So it is very hard to fathom what happened,” said Li Xiaojin, a Chinese aviation expert.

Online weather data showed partly cloudy conditions with good visibility in Wuzhou at the time of the crash.

President Xi Jinping called for investigators to determine the cause of the crash as soon as possible, state broadcaster CCTV reported.

Boeing said in a statement that its thoughts were with the passengers and crew.

“Boeing is in contact with the US National Transportation Safety Board and our technical experts are prepared to assist with the investigation led by the Civil Aviation Administration of China,” the company said.

A person familiar with the matter told Reuters that Boeing has cancelled a meeting of its senior executives scheduled for this week in Miami to focus on assisting the investigation and China Eastern Airlines.

Shares of Boeing Co were down 4 per cent on Monday.

The 737-800 has a good safety record and is the predecessor to the 737 MAX model that has been grounded in China for more than three years after fatal crashes in Indonesia and Ethiopia.

China’s airline safety record has been among the best in the world for a decade.

According to Aviation Safety Network, China’s last fatal jet accident was in 2010, when 44 of 96 people on board were killed when an Embraer E-190 regional jet flown by Henan Airlines crashed on approach to Yichun airport.