There was no immediate word on numbers of dead and injured.
A China Eastern Boeing 737-800 with 132 people on board crashed in a remote mountainous area of southern China on Monday, officials said, setting off a forest fire visible from space in the country's worst air disaster in nearly a decade.
Broadcaster CCTV said the accident involved a China Eastern Airlines Boeing 737 and occurred near the city of Wuzhou in Teng county.
It said rescuers had been dispatched and there was no immediate confirmation of numbers of dead and injured.
One villager told a local news site that the plane involved in the crash had "completely fallen apart" and he had seen nearby forest areas destroyed by a fire caused when the plane crashed onto the mountainside.
The Civil Aviation Administration of China (CAAC) said the aircraft lost contact over the city of Wuzhou. It had 123 passengers and nine crew on board. State media said earlier there were 133 people on board.
"At present, it has been confirmed that this flight has crashed," the CAAC said, adding that it had activated its emergency response and "dispatched a working group to the scene".
Shanghai-based China Eastern is one of China's top three airlines, operating scores of domestic and international routes serving 248 destinations.
A China Eastern Airlines Boeing 737-800 operating flight MU5735 has reportedly crashed near Wuzhou in southern China. Initial reports say 133 onboard.pic.twitter.com/iipgQYGkhK
The flight that crashed appeared to be Flight No MU5735 from Kunming to Guangzhou, according to data from flight-tracking website FlightRadar24. It showed the Boeing 737-89P rapidly lost speed after 0620 GMT before entering a sharp descent.
The plane stopped transmitting data just southwest of the Chinese city of Wuzhou.
Chicago-based Boeing Co. did not immediately respond to a request for comment.
The aircraft was delivered to China Eastern from Boeing in June 2015 and had been flying for over six years.
The twin-engine, single-aisle Boeing 737 is one of the world's most popular planes for short and medium-haul flights.
China Eastern operates multiple versions of the common aircraft, including the 737-800 and the 737 Max. It is one of China's three major air carriers.
The 737 Max version was grounded worldwide after two fatal crashes. China's aviation regulator cleared that plane to return to service late last year, making the country the last major market to do so.
China had enjoyed an enviable air safety record in recent years in a country serviced by new airlines established to match the country's breakneck growth over the last few decades.
A Henan Airlines flight crashed in northeastern Heilongjiang province in 2010, killing at least 42 out of 92 people on board although the final toll was never confirmed.
It was the last Chinese commercial passenger flight crash that caused civilian casualties. The deadliest Chinese commercial flight crash was a China Northwest Airlines crash in 1994 which killed all 160 onboard.
Serious questions asked about Boeing
The crash comes amid falling trust in Boeing after two crashes involving the planes in recent years.
The iconic company, created in 1916, introduced the commercial jet that made flying affordable for most people and for many years was the most popular supplier of aircraft to airlines around the world.
At any minute there are around 10,000 Boeing planes in service in more than 150 countries around the globe.
But that trust was shaken when two planes fell out of the sky killing hundreds, within months of each other — Lion Air Flight 610 which crashed in Indonesia in 2018, killing 189 people, and Ethiopian Airlines Flight 302 which claimed 157 lives when it crashed in Ethiopia.
What was extremely shocking was they were both brand new planes, the 737 Max.
Jon Ostrower, Editor in Chief of aviation publication The Air Current said: "Two crashes of brand new aeroplanes within five months of each other, that doesn't happen in modern aviation."
• Air New Zealand no longer uses Boeing 737s for its domestic routes, opting in 2015 for an Airbus A320 fleet. Qantas uses some 737-800s for transtasman flights.