A Boeing 737-800 aircraft of China Eastern Airlines carrying 132 onboard crashed in southwestern China, causing a mountain fire in the Guangxi region.

China Eastern flight MU5735 took off from Kunming to the port city of Guangzhou. According to flight tracking portal FlightRadar24, the aircraft descended steeply from its altitude of 29,100 feet before it crashed.

Videos posted on social media platforms showed a forest fire on a mountainside.

The number of casualties remains unclear as of Monday afternoon, state-run Global Times said, citing the official website of Civil Aviation Administration of China (CAAC) said.

Chinese President Xi Jinping has called for the immediate activation of the emergency mechanism for the plane crash, the report said, adding that rescue teams have been dispatched to the crash site.

There were 123 passengers and 9 crew members on board, according to Aviation Safety Network.

China Eastern Airlines' official website, mobile app and social media platforms were showing black and white to mourn the victims of the Boeing 737 plane crash.

Prime minister Narendra Modi took to Twitter to express grief over the crash. "Deeply shocked and saddened to learn about the crash of the passenger flight MU5735 with 132 on board in China’s Guangxi. Our thoughts and prayers are with the victims of the crash and their family members," Modi tweeted.

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