KAMCHATKA, Russia — Six people have died climbing the Klyuchevskaya Sopka volcano in Russia’s far east and six more are believed to be stranded on Sunday after freezing winds halted a rescue attempt.

The party of twelve, which includes two guides, set off to climb the 15,597 foot volcano on Tuesday but ran into trouble on Saturday when some of the group fell to their death at almost 13,800 feet, authorities say.

One person is thought to have a broken leg, authorities said.

Rescuers attempted to reach them on Sunday but had to turn back as severe winds prevented their helicopter from landing.

“They were scheduled to land at an altitude of 10,800 feet, but due to gale force winds at 67 miles per hour, they failed to do so, although two attempts were made a few hours apart,” rescuers said.

Temperatures on the mountain can reach as low as minus 7 Fahrenheit overnight.

Tatyana Yukhmanova, a representative from the local civil defence authority, said that rescuers will try to reach the group again tomorrow if weather conditions allow.

Klyuchevskaya Sopka is the tallest of over 160 volcanoes whose snowy peaks tower over Russia’s Kamchatka peninsula.

It forms part of a UNESCO World Heritage Site listed for its exceptional natural beauty.

Rescuers warn that the mountain, made up mounds of volcanic rocks mixed with snow and ice, is considered particularly hazardous to climbers due to its altitude and the risk of volcanic eruption.