On 22 May 2021, 21 professional runners died from hypothermia out of the 172 competing in a government-run 100-kilometre (62 mi) trail running race[note 2] held in the Yellow River Stone Forest in Jingtai County, Gansu, China.

The organizers were unaware of the scope of the disaster because they did not assign any staff between checkpoints and they did not know the distressed point was in mobile phone signal blind spots.

[2] The race was jointly organized by the sports department of Baiyin prefecture-level city and the Communist Party Committee [zh] of Jingtai County annually from 2018.

The actual on-field event coordinator was the "Yellow River Stone Forest Administration", which is headed by the publicity chief of Jingtai County's Communist Party Committee, who later committed suicide (see § Disciplinary action).

[3] The 100-kilometre (62 mi) trail was set along Mijiashan Hill of the Yellow River Stone Forest, a treeless karst terrain at the transition from the Loess Plateau at its south to the Tengger Desert at the north.

The most rugged and narrow section, i.e. the second and third checkpoints, were not car-accessible and required 1–2 hiking hours from the nearest roads in the best weather conditions.

"[4] The provincial meteorological center, at an unknown time on the day before, flagged a key notice that warned of "21–22 May is forecasted to have massive yellow dust and sand carried by winds, a drop of temperature and some precipitation.

From 10:30, the north-facing third checkpoint, with an elevation of 2,230 metres (7,320 ft), was hit by a cold front originated from Mongolia via the Tengger Desert off Jingtai.

While many runners reported sightings of hail and freezing rain, the investigation concluded it was most probably graupel because the weather conditions were impossible for the former two to exist.

[14] Seldom experienced inland; trees uprooted The operator of the race, which was a local sports marketing company, had equipped runners with GPS devices.

The first distress message was sent at 11:50 (Nationwide Beijing time[note 1]) by a runner via GPS, but never received a response.

[3] An ill-equipped private search team called Blue Sky Rescue (蓝天救援队), stationed at the starting line, sent some of its 39 members to the hill between the second and third checkpoints.

Around 13:00–14:00, while his sheep insisted on grazing in cold, windy, rainy weather at the Mijiashan Hill, he spotted the stricken runners, some already collapsed unconsciously from hypothermia.

[3][17][18][19] At 14:30, the Yellow River Stone Forest Administration phoned the mayor of Zhongquan town with a brief instruction, "we need to bring winter supplies to the athletes".

The firefighters were not geared or trained to identify hypothermia, and did not attempt to perform CPR on the runners who "looked dead".