What you need to know:
- China's top sports body also vowed to tighten safety rules on holding events across the country.
- Survivors gave shocking testimony of events on the rugged mountainside, where unconfirmed meteorological reports to local media said temperatures had plunged to as low as minus 24 degrees Celsius (minus 11 degrees Fahrenheit).
An investigation was underway Monday into the deaths of 21 runners during a mountain ultramarathon in northwest China, as harrowing testimony emerged from survivors who battled to safety through freezing temperatures and bone-chilling winds.
The extreme weather struck a high-altitude section of the 100-kilometre (62-mile) race held in the scenic Yellow River Stone Forest in Gansu province Saturday afternoon.
Provincial authorities have set up an investigation team to look into the cause of the incident, state media reported, as questions swirled over why organisers apparently ignored extreme weather warnings from the city's Early Warning Information Centre in the lead up to the race, which attracted 172 runners.
China's top sports body also vowed to tighten safety rules on holding events across the country.
Survivors gave shocking testimony of events on the rugged mountainside, where unconfirmed meteorological reports to local media said temperatures had plunged to as low as minus 24 degrees Celsius (minus 11 degrees Fahrenheit).
"The wind was too strong and I repeatedly fell over," wrote race participant Zhang Xiaotao in a Weibo post.
"My limbs were frozen stiff and I felt like I was slowly losing control of my body... I wrapped my insulation blanket around me, took out my GPS tracker, pressed the SOS button and lost consciousness."
He said when he came round he discovered a shepherd had carried him to a cave, placed him by the fire and wrapped him in a duvet.
'Foaming at their mouths'
Marathon survivor Luo Jing told state broadcaster CCTV she saw runners struggling back down the mountain wearing only T-shirts and shorts.
They "described to us people foaming at their mouths, and urged us to quit the race as soon as possible," she said.
Other survivors said insulation blankets provided by organisers were blown to shreds by strong winds.
One told state media as he battled down the mountain he saw many people lying on the ground, some he believed to be dead.
Gansu province, which includes part of the Gobi desert, is often subject to extreme weather conditions including sandstorms.
Baiyin city, where the race was held, reaches up an elevation of more than 3,300 metres (11,000 feet).
The Gansu Meteorological Bureau had warned of "sudden heavy showers, hail, lightning, sudden gale-force winds" and other adverse weather conditions across the province in a report dated Friday.
Victims included elite Chinese long-distance runners Liang Jing and Huang Guanjun, local media reported.
Liang had won multiple Chinese ultramarathons in recent years while Huang won the men's hearing-impaired marathon at the 2019 National Paralympic Games.
Fury mounted on Chinese social media after the disaster, with many users blaming organisers for poor contingency planning.
More than 84 million viewed the hashtag "Is the Gansu marathon accident natural or man-made?", while 130 million scoured a thread around safety concerns for marathons and cross-county races.
"This is purely a man-made disaster," wrote one.
China's top sports governing body has issued instructions to the country's sports system to improve safety management in sports events.
The previous management model for safety in races "had some problems and deficiencies", the sports administration said in a readout published Monday, and said all organisations would now have to set up detailed contingency plans and a mechanism to halt the event quickly if needed.