Extreme weather in China has left 21 cross-country runners in the northwestern part of the country dead, according to reports.

The athletes were in the high-altitude section of the race in the Yellow River Stone Forest near Baiyin city when “abrupt, extreme weather” struck about 1 p.m. Saturday, local officials said.

Hail, “ice rain,” strong winds, and with frigid temperatures, quickly took hold, said Baiyin city mayor Zhang Xuchen.

Of 172 runners taking part in the 60-mile race, about 151 were found safe. The contest was called off when the runners were endangered, state news agency Xinhua said.

The bodies of those killed were found by rescuers on Sunday.