HOUSTON -- Texas authorities are investigating the death of a 30-year-old man whose body was recovered Sunday from Dallas-Fort Worth’s Trinity River after he disappeared while competing in an outdoor obstacle race called the “Original Mud Run.”

It was still unclear Tuesday how Tony Weathers died, investigators said.

Staff at the Tarrant County Medical Examiner’s Office conducted Weathers’ autopsy Monday, but Fort Worth police were still awaiting toxicology results Tuesday, Sgt. Pedro Criado told the Los Angeles Times.

Homicide detectives were awaiting the medical examiner’s ruling to determine whether they need to investigate further, Criado said.

The “Original Mud Run” is an outdoor obstacle race, less strenuous than an Ironman, but muddy like other outdoor races such as the Warrior Dash or Tough Mudder.

The Mud Run includes both 5K and 10K obstacle courses, each with a slew of water and mud obstacles, including “Hole to Hades,” “Leap of Faith” and “Stairway to Heaven.”

About 4,000 racers participated in Saturday’s event, starting in heats of 400 every half hour.

After Weathers -- known to training partners as “Weatherman” -- started the 10K race in the competitive division at 2 p.m. Saturday, one of the first obstacles he faced was a 150-foot swim across the Trinity River. Friends waited on a nearby bridge to cheer him on and take pictures, but told WFAA they never saw Weathers swim past.

Weathers’ girlfriend waited at the finish line, and when he still had not shown up hours later, alerted race organizers, according to ABC News.

“The fire department went out Saturday evening around 5 o’clock when we were first notified,” Timothy Hardeman, engineer and spokesman for the Fort Worth Fire Department, told ABC News.

Dive crews found a body in the river Sunday morning, not far from the race course, Criado said.

“I just don’t know how it happened. He’s strong enough to pull himself out of that water,” Lynetta Moore, Weathers’ personal trainer, told WFAA. “I don’t know if he was trampled, tangled, but it doesn’t make sense. Totally out of character for someone with that level of athleticism. Something went wrong.”

Moore did not return calls Tuesday.

Officials with the group expressed condolences in a Sunday statement posted on Facebook, but noted that lifeguards and water safety devices were on hand to aid participants as they swam.

“We work closely with local authorities to ensure we meet or exceed all of the necessary requirements for safety,” the statement said. “With any of our obstacles that involve river crossings or swimming we provide alternate routes, swim assist devices, guide ropes, floating platforms and certified life guards. In addition we make multiple announcements prior to the race, during the registration process and prior to the start of each wave regarding safety and encourage all participants to either skip or choose the alternate route should they feel unsure or feel that they cannot complete an obstacle.”

Organizers said that four certified lifeguards were posted at the race’s first river crossing: one at the entrance to the water, one at the exit and two on a floating platform in the middle of the river. Another lifeguard was posted at the second river crossing with a volunteer certified in advanced cardiac life support, CPR and first aid, they said.

Organizers also had a roving EMT and medic on hand, another team of medics, Fleet Marine Corpsmen, registered nurses and a two-person first aid trailer. Along the course, 50 to 100 volunteers were assigned to spot people in need of first aid.

Some racers commented on Facebook that they noted the safety measures in place.

“I ran at 9:30 and saw lifeguards at both passings helping people,” wrote Marne Godfredsen Brand. “I’ve heard many having issues with panicking people pulling others down. Sounds like just a lot of different perceptions. Maybe just not enough for the number of runners. I’ll be back to the next run!”

Others criticized organizers for posting too few lifeguards on the river and not monitoring safety in the water closely enough.

“When I went, I could not tell who was a lifeguard. I saw one guy starting to drown ... his head went under, and he was panicking. It was the other runners that helped him back to the shore, no lifeguards,” wrote Alex Marrs, adding, “There were no floats. The noodles had been either lost, or were on the other bank of the river.”

Weathers’ death is the first fatality in the race’s 14-year history, but not the first for extreme obstacle races.

Two Warrior Dash participants, ages 28 and 31, died after participating in a 3.1-mile race in Kansas City, Mo., last July which included mud pits, cargo nets and fire, according to the Topeka Capital-Journal. More than a dozen other racers were hospitalized due to the extreme heat.

On the same weekend, a 21-year-old college student was paralyzed from the chest down after diving into a mud pit at another Warrior Dash event in Genesee Township, Mich., the Capital-Journal reported.

Original Mud Run officials have said their next race in Houston is still scheduled for May 26.

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