The race began 9 a.m. local time Saturday in the northwestern province of Gansu.
An ultramarathon is any long-distance race that extends beyond the standardized (since 1921) marathon length of 26 miles 385 yards. The race in China was set for 62 miles through tough terrain that included cliffs and canyons, Reuters reported.
Forecasts had called for wind and rain, but nothing as serious as what racers met.
Three hours after the start, temperatures plummeted as hail, high winds and freezing rain struck the course. Temperatures hit a low of 43 degrees Fahrenheit – not including wind chill.
Officials halted the race after 172 runners went missing.
More than 1,200 rescuers, assisted by thermal-imaging drones and radar detectors, deployed across the area, recovered151 runners safely. Eight were injured. The remaining racers were found dead at various points along the course, with the latest victim discovered Sunday morning.
Rescue efforts faced further complication due to a landslide after the rain, The New York Times reported.
The search continued into Sunday morning, with further temperature drops making the search more difficult. Many of the runners suffered from hypothermia.
Baiyin City Mayor Zhang Xuchen said Sunday that provincial authorities will further investigate the incident, but Chinese social media exploded with outrage directed at the local government for not planning more carefully, the Guardian reported.
"Why didn’t the government read the weather forecast and do a risk assessment?" one commentator wrote.
"This is totally a man-made calamity. Even if the weather is unexpected, where were the contingency plans?"
Baiyin city officials publicly accepted blame during a press conference Sunday.
"As the event organizer, we feel deeply guilty," Mr. Zhang said. "We express our sorrow for the victims and our deep condolences to the families of the victims and the injured."