UPDATE: Col. Gene Montague's brother says his family is still in shock to learn Montague suffered a heart attack during the IRONMAN swim because he was "so very healthy" and "he loved these events."

The preliminary autopsy report says Gene Montague, 51, passed away during the IRONMAN competition from a heart attack and his death has been ruled accidental. The report says Montague died "suddenly when in apparent health."

The Hamilton County Medical Examiner's office was told Montague was seen floating during the swimming portion of the race, was pulled from the water and was given CPR.

Family and friends of Col. Montague are posting heartfelt tributes on social media about his passion for athletics and his loving family.

Col. Montague's brother, Rashid Basir, said they are planning a funeral at Arlington Cemetery with full military honors. Col. Montague was still active duty in the U.S. Army and was a combat veteran of Kosovo and Afghanistan. Before he joined the Army, Montague was a New York City Police Officer.

An IRONMAN 70.3 teammate said Col. Montague was participating in Sunday's event for Team ZERO that included athletes from all over the country. They were all competing to raise money to end Prostate Cancer.

"He was strong, he was a competitor, he was fierce and I wouldn't have guessed it could happen, but that's just the reality of life, you just don't know," said Team ZERO teammate Jon Pierson.

Pierson said he was with him just before the race started.

"By the point I had met with Gene we were in the swim start line and we were just a minute from jumping in the water," he said.

Pierson was nervous for the race and said Montague could tell. Before jumping into the water Montague turned to his new friend and gave him a high-five.

"And at that point I was just so fired up and that high five is just a special moment and how I'm going to remember Gene," Pierson said.

Once Montague started the swim portion of the race, tragedy struck.
Montague's family said they are still shocked to learn he died of a heart attack because he lived such a healthy and active lifestyle.

But Dr. Charles Campbell, Chief Cardiologist of Erlanger, said even though healthy people are at a lower risk for a heart attack, it can still happen to anyone.

"There aren't always warning signs, sometimes this is just bad luck, and in about 20 - 25 percent of the cases people don't seem to have a warning sign that they're going to have a big heart attack," Dr. Campbell.

PREVIOUS STORY: Erlanger officials treated 143 people during Sunday's IRONMAN 70.3 triathlon. 

About 15 of those came from the Tennessee River during the swimming portion of the race. It's also where one man died. 

Not long after the race kicked off, tragedy struck the Tennessee River when a participant suffered a medical emergency during the triathlon's swimming portion. 

Emergency responders rushed to get him out of the water, performed CPR and took him to Erlanger Hospital where he later died. 

Responders from Dallas Bay Fire Department were one of many local departments staged along the Tennessee River throughout various portions of the 1.2 mile course. 

Assistant Chief, Jack Brellenthin says they treated a number of injuries including crams, dehydration and shortness of breath. 

With more than 3,000 participants in the water, Brellenthin says it can be tough getting to those who need help without good logistics. 

"Just identifying people that might be in trouble and then the logistics involved and beginning treatment as soon as you can and then transporting them to the advanced life support ambulances," he said. 

Hospital officials say five participants were taken to the hospital for injuries and more than 130 were treated for injuries on site. 

Race officials have not released the man's name or how he died. 

A man has died while competing in the Ironman 70.3 Chattanooga, Sunday. 

Ellie Siefert, Public Relations Director for Ironman released this statement in regards to the athlete's death: 

"We are deeply saddened to confirm the death of one of our athletes participating in today's IRONMAN 70.3 Chattanooga triathlon. The athlete required medical attention during the swim and was transported to a nearby hospital where they were treated. Our condolences go out to the athlete's family and friends, whom we will continue to support."

The man was pulled from the water via Hamilton County EMS. The man will not be identified until family is notified 

Stay with Channel 3 as this story develops.