The incident occurred at 8:49 AM Seoul time while Yoo was competing in the half marathon (21,0975 km). She lost consciousness and fell to the ground around the 21st kilometer mark. On-site medical teams immediately performed cardiopulmonary resuscitation (CPR) and called an ambulance. Yoo was quickly transported to the hospital, but she did not survive.

On 12/10, the Seoul Race organizers announced the incident, extending condolences to the victim's family and participants of the race. The organizers stated they would continue to review related circumstances and implement necessary measures following the incident.

Yoo running at the Seoul Marathon on 15/3. *Photo: Naver*

According to Seoul Shinmun and NewsPim, the exact cause of Yoo's collapse and death has not been released. Some Korean news reports used the term "cardiac arrest", but there is currently no official medical conclusion regarding the cause of death.

Yoo Ji-won, born in 2001, was a well-known figure in the Korean running community.

She was a graduate student at the Korea Advanced Institute of Science and Technology (KAIST), specializing in semiconductor research for artificial intelligence (AI). Beyond her academic pursuits, she regularly participated in races and shared her training experiences on social media.

Yoo began running in 2022 but only focused on improving her performance from summer 2025. In a YouTube interview in 3/2026, she mentioned often being at the research lab from 9h, dedicating time to her studies and research before starting a run lasting about two hours from 20h. On some days, after training, she would return to the lab to finish her work.

Although not a professional athlete, Yoo achieved impressive running statistics. At the Seoul Marathon on 15/3, she completed 42,195 km in 2 hours 56 minutes 32 seconds, reaching the sub3 milestone with an average pace of about 4:11 (4 minutes 11 seconds per km). Also in March, she achieved 1 hour 22 minutes 1 second at the New Balance Half Marathon, equivalent to a 3:53 pace.

Yoo's sub3 achievement certificate from the Seoul Marathon on 15/3. *Photo: Chosun*

Her personal best for the 10 km distance was also recorded at around 36 minutes. On 5/4, Yoo won the amateur women's 10 km event at the Gunsan Saemangeum Marathon 2026. These results helped her become known as one of the most outstanding amateur female runners in South Korea.

Many runners participating in the Seoul Race on 11/10 expressed sorrow upon learning the victim's identity. One runner stated they were running behind Yoo in the final kilometers but then lost sight of her and felt concerned. "I want to remember her as a runner who always gave her best until the very end," this person wrote in a social media tribute.

Another person recounted witnessing medical staff performing CPR on Yoo, but only learned the victim was Yoo when the information was released. Many who had followed her training videos also offered their condolences.

This year's Seoul Race was the 24th edition, attracting approximately 12,000 athletes participating in two distances: the half marathon and 11 km. The course passed through many famous landmarks in the heart of the South Korean capital, such as Seoul Plaza, Gwanghwamun, and Dongdaemun.

By Nhat Tao