Residents watch as a China Eastern passenger jet prepares to take off on a test flight from the new Beijing Daxing International Airport on Monday. AP

China Eastern has confirmed there are fatalities after a jet carrying 132 people crashed into a mountain in southern China on Monday, shortly after losing contact with air traffic control and dropping thousands of metres in just three minutes.

The Boeing 737-800 flight from the city of Kunming to the southern hub of Guangzhou "lost airborne contact over Wuzhou" city in the Guangxi region on Monday afternoon, according to the Civil Aviation Administration of China (CAAC). The jet was carrying 123 passengers and nine crew members.

China Eastern confirmed that at least some people involved in the crash had been killed, without providing more information.

"The company expresses its deep condolences for the passengers and crew members who died in the plane crash," the airline said in a statement.

The disaster prompted an unusually swift public reaction from President Xi Jinping, who said he was "shocked" and ordered an immediate investigation into its cause.

Hundreds of firefighters were dispatched to the scene in Teng county near Wuzhou, state media reported, as nearby villagers rushed to help the rescue effort.

"Everyone went to the mountains," Tang Min, who runs a restaurant a few kilometres from the crash site, told AFP by telephone.

Fears for the fate of the jet spread on Monday afternoon as local media reported that Flight MU5735 had not arrived as planned in Guangzhou after taking off from Kunming shortly after 1:00pm.

Some Chinese media carried a video that appeared to show a plane in a vertical nosedive. AFP could not immediately verify the authenticity of the video.

One villager told a local news site the plane had "completely fallen apart" and he had seen forest areas destroyed by the fire caused by the crash.

Another villager surnamed Liu told state-run China News Service that he had driven his motorbike to the scene after hearing a loud explosion, and seen scattered debris including an aircraft wing and scraps of clothing.

Aerial images of the crash site showed a large crater in the side of a green mountainside. State TV footage followed orange-clad emergency workers battling thick foliage to gather debris.

'Waiting for news' 

President Xi called for all-out rescue efforts and to determine the "cause of the accident as soon as possible," according to CCTV, calling for "the absolute safety of the sector and people's lives."

The arrivals board at Guangzhou airport showed the jet's flight information for hours after it had crashed, as staff in full PPE held up signs to direct distraught relatives to a separate waiting area.

The area was marked by high black screens emblazoned with the word "emergency" and guarded by officials and police. AFP reporters could see loved ones awaiting news and heard sobbing.

Pakistan PM Imran expresses grief over plane crash in China

Pakistan Prime Minister Imran Khan expressed grief for the China Eastern Airline's plane crash, Boeing 737-800 carrying 133 people, into a mountain in southern China.

"Deeply saddened by the tragic loss of lives in the passenger plane crash in China," the prime minister said as the disaster prompted an unusually swift public reaction from Chinese President Xi Jinping, who said he was "shocked" and ordered an immediate investigation into its cause.

"We share the grief of our Chinese brothers and sisters and convey our deepest condolences and sympathies with the bereaved families," Imran Khan said.