“The GoPro was proved to be like the black box of an aircraft giving an insight into the last few moments of the climbers,” A.P.S. Nambadia, deputy inspector general of the Indo-Tibetan Border Police, said at a news briefing, according to the BBC. “It was mesmerizing for us to see the footage,” he added.

By the time the Nanda Devi group went missing, it had already been a deadly spring in the Himalayas, with a series of deaths associated with a traffic jam near the peak of Mount Everest. A picture spread on social media showing a line of up to 300 people crowding a dangerously narrow path, after Nepal issued a record number of permits and the weather cleared for an extended period.

According to border officials, the group of climbers shown in the video released on Monday may have triggered an avalanche by the weight of their bodies. The clip could help investigators determine what exactly went wrong.

Rescuers reached the bodies of the seven buried in the snow on Nanda Devi, which is northeast of Everest, on June 23 in an operation called “Daredevils.” The border authorities called it a “never before seen operation,” one of the most challenging that mountaineers in the area had undertaken.