Two helicopters collided Tuesday while trying to land just below Mount Everest’s base camp, killing at least one person and injuring two others, officials said.

The aircrafts were ferrying trekkers who had been hiking up to Everest base camp during Nepal’s popular trekking season.

Heavy snow had covered the route before the weather improved Sunday and thousands of trekkers were able to move around.

There are no roads on Everest, and helicopters are the only way to bring down trekkers and guides who become sick or exhausted in the cold and high altitude.

The helicopters crashed at Pheriche village, which is at 4,200 metres (13,780 feet) altitude.

A 47-year-old tourist from India was killed in the crash, according to Bhupendra Thapa, a Solukhumbhu district administration officer.

A passenger from New Zealand was injured and was being transported to the capital, Kathmandu, for treatment. A Nepali pilot sustained injuries but was treated locally.

The number of people on the two helicopters wasn’t clear.

The Mount Everest base camp trek lasts up to two weeks and goes from the only airstrip in the area at Lukla to base camp located at 5,300 meters (17,380 feet).

The trek is popular during the fall season, right after the rainy season and before the harsh winter months.