ST. LOUIS - A 17-year-old chess grandmaster was charged with assault after hitting a woman at a Saint Louis Chess Club tournament last week.

St. Louis Metropolitan Police told FOX 2 on Friday that grandmaster Christopher Yoo, 17, was charged with fourth-degree assault and released to one of his parents as directed by the juvenile courts.

According to the Saint Louis Chess Club, Yoo allegedly violated the code of conduct and safe play policies following a chess match loss. Yoo allegedly crumpled a scoresheet and stormed out of the tournament hall, striking a videographer from behind after the match last Wednesday.

In response, officials expelled Yoo for the remainder of the 2024 U.S. Chess Championship in St. Louis, which concluded Thursday, and additionally banned him from the Saint Louis Chess Club.

Event organizers say Yoo’s results from the first five rounds of the tournament will be declared invalid and tournament standings were adjusted accordingly.

“We take player conduct seriously and do not tolerate violations of our standards,” said the Saint Louis Chess Club in a statement last week. “We acted swiftly to address this situation, ensuring a respectful and safe environment for everyone involved in the tournament.”

Yoo apologized for his actions in a statement posted on his parents Facebook and further shared on the U.S. Chess Federation's website.

"First and foremost, Christopher wants to publicly apologize to the female videographer that was an innocent victim of his anger after his loss of a chess game. Contrary to what some have suggested, the videographer did nothing to provoke Christopher. We heard she’s doing okay but we don’t have any details and we pray she is doing well both physically and emotionally. Her well-being is of deep concern to all of us," the post said. "Christopher offers no excuses for his behavior. He is just very sad and ashamed he behaved in that way."

According to Chess.com, Yoo is a California native. He is considered one of the youngest American grandmasters with the highest title awarded in U.S. professional chess. Yoo earned a spot in the U.S. Championship in St. Louis by winning the 2024 U.S. Junior Chess Championship.