Hundreds of people were trapped on Mount Everest after heavy snow over the weekend, according to the Chinese authorities, prompting a closure of the scenic area during a national holiday that had drawn large numbers of tourists to the site.

The local government of Shigatse, a city in Tibet that includes the Chinese side of Mount Everest, said in an announcement on Sunday night that rescue workers were in touch with the stranded hikers, and that they had sufficient supplies, without saying for how long. It did not specify how many people were still on the mountain either. (Mount Everest is on the border of China and Nepal, and the eastern slopes are in Tibet.)

China’s central broadcaster reported on Sunday that 350 people had arrived safely at a rescue point in the town of Qudang in Tibet, and that over 200 others were on their way there. Reached by phone on Monday, staff members at several local tourism authorities said they were unclear about the state of the rescue operation.

Footage obtained by Reuters showed a line of hikers trekking through the snow on Sunday, with apparently poor visibility as snow continued to fall. Another video filmed from inside a tent, showed that the tent’s ropes were partly buried.

The snow began during the night on Saturday, according to the local government announcement. It buried tents at a campsite at an elevation of more than 4,900 meters, or 16,000 feet, on the mountain’s eastern slope, and left some hikers with hypothermia, according to Chinese Communist Party-controlled Metropolitan Express News, based in the city of Hangzhou.

The Mount Everest Scenic Area as well as surrounding tourist attractions were closed until further notice because of icy roads and unsafe conditions, according to a notice posted on social media by the area’s operators.

Shangyou News, a party-controlled outlet based in the city of Chongqing, said that the snowfall was the heaviest in recent years to fall during the weeklong holiday around China’s National Day on Oct. 1.

Chen Geshuang, a hiker who was safely evacuated to Qudang, told Reuters that her guide said he had never encountered such weather in October.

Mount Everest has become an increasingly popular site for Chinese visitors in recent years, as the government has poured money into building tourist infrastructure. Last year, more than 540,000 people visited the area, setting a record, according to Chinese state media.

Siyi Zhao contributed research.