An experienced backcountry skier has died of an apparent heart attack while on the slopes with his friends.
Bernard 'Bernie' Rosow, 45, collapsed while climbing Bloody Mountain, located in California's Sierra Nevada mountain range, on Thursday morning.
The group of skiers were heading to the summit ridge at about 11,400 feet when Rosow abruptly sat down, complained of sudden back pain and became unresponsive, a witness told SFGate.
The skier's friends started performing CPR on him and contacted 911, prompting a massive rescue from a 'hasty team' of emergency responders.
Rescuers descended on the mountain in helicopters and snowmobiles. Rosow's friends continued heart compressions for hours as they waited for help to arrive.
Despite the 'strong and extensive efforts' of both Rosow's friends and the rescuers, he was pronounced dead at the scene, the Mono County Sheriff's Office said.
Rosow, a native of southern Vermont, was a ski influencer and longtime employee and snowcat operator at Mammoth Mountain resort.
He is survived by his partner Amber Feld and their eight-year-old son Alexander.
Bernard 'Bernie' Rosow, 45, died of an apparent heart attack on Thursday after he collapsed while climbing Bloody Mountain
The experienced backcountry skier is survived by his partner Amber Feld and their eight-year-old son Alexander, pictured together
Feld announced Rosow's death Friday in a heartbreaking Instagram post, writing: 'We lost Bernie yesterday.
'Alexander's favorite person in the whole world, and my love. He was out doing what he loves to do hiking with friends up Bloody Mountain to ski down.'
She shared how Rosow suffered a 'heart health incident and passed quickly.'
Feld recalled how when she and Rosow first met 15 years ago, he told her that he planned on hiking Bloody Mountain.
She said that even now the mountain remained one of his favorite places.
'Last weekend he told Alex the mountain got its name because of its red rocks,' she wrote.
'Bernie we will always live in your spirit. This has always been Alex's favorite photo of us. We love you so much.'
She went on to thank 'the people that were with Bernie in his final moments, and everyone that helped out that day.'
Rosow, a native of southern Vermont, was a ski influencer and longtime employee and snowcat operator at Mammoth Mountain resort
Rosow and his friends were heading to the Bloody Mountain summit ridge, pictured, at about 11,400 feet when he abruptly sat down, complained of back pain and became unresponsive
Adventure sports photographer Christian Pondella, who was on the mountain with Rosow, said the entire tragedy unfolded quickly.
'Everything was normal, just a typical day. Just out of the blue he said, 'My back hurts, it hurts between my shoulders,' Pondella told SFGate.
'It happened so quick,' he continued. 'Two minutes before that he was having normal conversations.'
Rosow learned to ski as a toddler and moved to the West Coast when he was 18 to pursue a career in skiing and outdoor adventure.
He moved to Mammoth Mountain in the early 2000s and slept in a tent in the woods until he managed to land a job as a snowcat operator, he told the Blackmail ski magazine last year.
'I told everyone I wanted to ski every single day it snowed, I wanted to be the first person in the lift line, and I didn't want to talk to people at work,' Rosow said. 'They told me I should be a cat driver.'
He previously dreamt of being a professional skier, but told the magazine he could not afford the travel required to 'pursue it seriously.'
He instead spent more than 25 years working at Mammoth Mountain and has skied powder every day for the last 20 years, except on the day of his son's birth.
According to his TikTok profile, Rosow lived by the philosophy of 'work all night to ski all day.'
Feld recalled how when she and Rosow first met 15 years ago, he told her that he planned on hiking Bloody Mountain. She said that even now it remained one of his favorite places
Rosow, with his son, spent more than 25 years working at Mammoth Mountain and has skied powder every day for the last 20 years, except on the day of his son Alexander's birth
He is understood to have routinely worked 70-hour weeks in which he skied during the day and maintained the slopes at night.
He had become one of the resort's most popular skiers and amassed a TikTok following of more than 100,000 followers.
Mammoth Mountain Ski Area spokesperson Emily van Greuning, in a statement to SFGate, said he will be 'missed greatly' by the entire resort community.
'His passion for the sport was aspirational, and his legacy will never be forgotten. Our thoughts are with his family, friends and colleagues during this difficult time,' van Greuning wrote.
The Daily Mail has approached Feld, the Mono County Sheriff's Office and Mammoth Mountain for comment.