Nearly 10,000 air passengers were stranded and 130 flights delayed due to a heavy fog that blanketed Chengdu, Sichuan's provincial capital, on early Thursday.

After 7:00 a.m., the fog cut visibility at Chengdu Shuangliu International Airport to less than 50 meters, far below the 550 meters and 800 meters required for planes to take-off and land, respectively.

Airport authorities have activated an emergency response and issued a yellow alert for massive flight delays.

For safety concerns, Chengdu Airport was forced to shut down after flight 3U8333 departed at 7:08 a.m., which reopened two hours later with flight 3U8905 leaving for Yangzhou at 9:19 a.m., the airport authority said.

The temporary closure has grounded more than 130 flights and stranded nearly 10,000 passengers at the airport.

During this time, 12 incoming flights rerouted to airports in neighboring Chongqing and Guiyang.

The airport said it will provide water and breakfast to stranded passengers.

These conditions have resulted in unprecedented congestion at Chengdu Airport and will lead to knock-on delays for most flights of today, the airport source said.

Airport operators made efforts to maintain order and arrange accommodations for the stranded passengers.