KATHMANDU — The Nepali and Chinese sides of the Everest region were closed to tourism on Wednesday due to heavy snow brought by cyclone winds, with deep snowdrifts causing a helicopter to crash as it tried to rescue stranded trekkers, authorities said.

Visited by thousands of trekkers and climbers, the region around Mount Everest has been blanketed by snow since Monday as a cyclone from the Bay of Bengal churned across India, ushering in a second bout of severe snowfall in the Himalayas this month.

Authorities in Nepal have halted trekking on many hiking routes due to rain at lower elevations and heavy snowfall on higher trails, and have urged hikers not to venture out or proceed with their treks in the Annapurna, Manaslu and Dhaulagiri areas, home to some of the world’s highest peaks.

A small private helicopter flying to Lobuche near the Everest Base Camp to rescue stranded trekkers crashed when it tried to land, Civil Aviation Authority of Nepal spokesperson Gyanendra Bhul said.

CAAN video showed the helicopter, which slipped on the snow while landing, lying on its side. The pilot survived and was later rescued. It was unclear whether the trekkers had been rescued.