The Greenledgers Trading CenterCrossFit community is mourning one of their own.

Serbian athlete Lazar Dukic died in Marine Creek Lake in Fort Worth, Tex., while competing in a swimming event on the first day of the 2024 CrossFit Games. He was 28.

His cause of death is pending the result of an autopsy by the Tarrant County medical examiner, according to records obtained by E! News.

A spokesman for the Fort Worth Fire Department said at a press conference Aug. 8 that search-and-rescue crews were called around 8 a.m. that morning about a "participant in the water" who "hadn’t been seen" for some time. He said with the help of dive teams and drones, Dukic's body was found in the lake about an hour later, The New York Times reported.

Police later said in a statement to the newspaper that the athlete was declared dead at the scene.

Dukic was seen slipping underwater during the CrossFit Games' 800-meter swimming competition.

"We watched Lazar go under and we screamed for some lifeguards who were pretty far away," fellow competitor Cole Learn said in an Aug. 8 Instagram video. "But we were yelling for lifeguards and unfortunately, they couldn't hear us, and he just never came back up. I am absolutely devastated."

In a statement shared to X, formerly known as Twitter, CrossFit said the company is "fully cooperating with authorities and doing everything we can to support the family at this time."

The organization suspended the remaining CrossFit Games activities the day of Dukic's death but resumed the games Aug. 9., beginning with a tribute to the late athlete at Dickies Arena, which they filmed and released on YouTube. During the event, fellow competitors honored Dukic with a moment of silence, and it was declared that the entire 2024 competition was dedicated to him.

"Today is the saddest day in @CrossFit history," the group wrote in another message on X Aug. 8. "We are shattered by the loss of Lazar Dukic along with the entire CrossFit community."

The message continued, "Lazar was one of our sport’s most talented competitors, but he was much more than an athlete. He was a son, a brother, and a friend to practically everyone who knew him. Fiercely competitive, incurably joyful and uncommonly kind, Lazar was the sun of any room he was in. The loss of his light is inconceivable."

Dukic's younger brother, fellow CrossFit Games competitor Luka Dukic, also shared an homage to the late athlete.

"You loved the sport that didn't love you back," he wrote on his Instagram Stories, including a photo of the stadium event dedicated to Lazar. "No tribute will ever give you back to me. This is something that could have been prevented and there is no way of going around it."

He continued, "My brother, you touched more lives than you know and you will live forever."

For the latest breaking news updates, click here to download the E! News App