Two Japanese boxers have died from brain injuries suffered in separate bouts during the same fight card in Tokyo, an incident officials say is unprecedented in the country’s boxing history.

Super featherweight Shigetoshi Kotari and lightweight Hiromasa Urakawa, both 28, fought on August 2 at Korakuen Hall. Both were later rushed to hospital and underwent emergency brain surgery.

Kotari, who went the distance in a 12-round draw against fellow Japanese fighter Yamato Hata, collapsed shortly after the fight. His M.T boxing gym announced he died at 10:59 p.m. on August 8 from acute subdural haematoma. “He did his best to fight his way through the surgery and treatment he had been receiving at a Tokyo hospital,” the gym said.

Urakawa was stopped in the eighth and final round against Yoji Saito. The World Boxing Organisation (WBO) confirmed his death in a statement on Sunday, saying he had “tragically succumbed to injuries sustained during his fight.” Local media reported he died on Saturday night.

“This heartbreaking news comes just days after the passing of Shigetoshi Kotari, who died from injuries suffered in his fight on the same card,” the WBO said, offering condolences to their families, friends, and the Japanese boxing community.

Japan Boxing Commission Secretary-General Tsuyoshi Yasukochi said it was likely “the first time in Japan two fighters underwent skull-opening surgery for injuries stemming from the same event.”