Another 151 participants were confirmed safe, of which eight with minor injuries were treated in the hospital and in stable condition.
It was a public safety incident caused by a sudden change in local weather, and the province had set up a special team to further investigate the cause of the incident, said Zhang Xuchen, mayor of Baiyin City, at a press briefing on Sunday morning.
The marathon race was held on Saturday morning in the Yellow River Stone Forest tourist site in Jingtai County, Baiyin City.
According to the rescue headquarters, at about 1 p.m. Saturday, hails, freezing rain and gales hit the area of the race's high-altitude stage between 20 to 31 km. Participants suffered from physical discomfort and loss of temperature due to the sudden drop in air temperature.
Some of the participants went missing and the race was halted.
Local governments initiated an emergency response and organized over 1,200 well-equipped rescuers to search for the missing people.
The temperature dropped again during the night due to the area's complex terrain and topography, making the search and rescue more difficult.
A total of 172 people took part in the mountain marathon race.
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