USA Track and Field announced Lee Evans, a former world record holder and gold medalist sprinter, died on Wednesday. He was 74 years old.
His cause of death has not been announced.
Evans suffered a stroke last week in Nigeria and was unconscious in a hospital as of Sunday, according to the San Jose Mercury News.
Evans won two gold medals at the 1968 Summer Olympics in Mexico City while competing in the 400-meter dash and the 4x400-meter relay. He set world records in both events that stood for over 20 years.
He was the first man to run the 400-meter dash in under 44 seconds and was inducted into the United States National Track and Field Hall of Fame in 1983.
Evans was also a humans rights activist who, along with other U.S. sprinters like Tommie Smith and John Carlos, considered boycotting the 1968 Olympics to protest racial injustice in America. Lee and Smith were subjected to death threats as a result.
The three San Jose State runners were nicknamed "Speed City" for their collegiate dominance and were all active in the Black Power movement.
The sprinters eventually decided to compete in the Olympics, where Smith and Carlos also won gold and bronze, respectively, in the 200-meter dash and raised their fist on the podium for the iconic Black Panther salute.
When accepting his gold medals, Evans and his teammates wore black berets, imitating members of the Black Panther Party.