By Ben Church and John Sinnott, CNN
(CNN) - Pioneering ski mountaineer Hilaree Nelson has gone missing during an expedition in Nepal, according to one of her sponsors.
The 49-year-old American, who has enjoyed a famed career spanning over two decades, reportedly disappeared below the summit of Nepal's Mount Manaslu -- the world's eighth-highest mountain.
"We are in touch with Hilaree's family and supporting search and rescue efforts in every way we can," apparel company The North Face, one of Nelson's sponsors, tweeted on Monday.
Nelson is a mother of two, and her partner is also an experienced ski mountaineer, Jim Morrison, according to The North Face. She had been skiing and exploring the Nepali mountain with Morrison when she was announced missing.
Jiban Ghimire, managing director of Shangri-La Nepal Trek, told Outside magazine that his crew received a call on Monday saying Nelson had fallen and was nowhere to be seen.
"I got a call from our staff at Base Camp that her ski blade skidded off and [she] fell off the other side of the peak," Ghimire told Outside.
Shangri-La Nepal Trek did not immediately respond to CNN's request for comment.
Last week, Nelson wrote an Instagram post about the challenges of the trip along with pictures of the expedition.
"I haven't felt as sure-footed on Manaslu as I have on past adventure into the thin atmosphere of the high Himalaya," she wrote, mentioning the bad weather which has plagued climbers in recent days.
"These past weeks have tested my resilience in new ways."
Morrison also posted on Instagram saying: "We went up high and tried hard but the mountain said no. Tails between our legs we bailed from camp 3 and head down, (on skis)."
Nelson is a pioneer in the mountaineering community and a role model to the new generation of climbers.
She has made first descents through more than 40 expeditions across the world and was named captain of The North Face Athlete Team in 2018.
In 2012, she became the first woman known to climb the world's highest peak, Everest, and also the adjacent mountain, Lhotse, in 24 hours.
She has continued to explore the world's mountains, often with Morrison, and pushed the limits of what is expected in the sport.
The Nepal Tourism Board did not immediately respond to CNN's request for comment.
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