Firefighter Thomas Seablom (left) and Sgt. Steven Denton (right) with the Quantico Fire Department helped save a man who almost drown as he swam in the Potomac River in a triathlon race. (Marine Corps Base Quantico Fire & Emergency Services)

They heard a woman scream for help. She was trying to keep her 83-year-old father, who was swimming in the Potomac River, afloat.

Fire Sgt. Steven Denton and firefighter Thomas Seablom raced to help. The firefighters with the Marine Corps Base Quantico Fire and Emergency Services unit were assigned to help monitor Saturday’s Quantico Tri race, and they saw a swimmer “waving her arms and yelling that she needed help” because another swimmer was “unresponsive in the water.”

The other swimmer in the water with her was her father, Thomas Tobias of Haymarket.

Tobias and his daughter, Ann Marie Chaney, were both competing in the triathlon. The swim was the first leg of the race and Tobias, who has double vision from a bicycle crash nearly two decades ago, said he was following the crowd in the open water. But after a while, the crowd started to thin and as he swam the backstroke to get a better look at the next bouy, he said a wave came over him and took him down.

He doesn’t remember much else.

Thomas Tobias, 83, of Haymarket smiles just before the Quantico Tri race. (Photo Courtesy of Shawn Chaney)

“We were just swimming and all of the sudden he went limp,” said Chaney, 51, of Bristow, who trained to be a lifeguard as a teenager. “And I grabbed him and treaded water with him — I stopped him from going under.”

The race included 200 swimmers doing the 750-meter race. Because there were so many swimmers, rescuers said, it was a challenge to navigate their boat through the swimmers in the river.

Seablom, who was at the helm of the 12-foot rescue boat, quickly maneuvered towards Chaney and Tobias.

Denton jumped into the water and got to Tobias. They pulled the 83-year-old into the boat and started doing CPR as they headed for shore.

“[We were] just in the right place, right time,” said Andre Hargett, who was also competing in the triathlon and helped give chest compressions to Tobias in the boat.

Once on land, the 83-year-old was taken to an area hospital in an ambulance. “We probably worked on him for five minutes,” Denton recalled.

Fire officials said the two rescuers saved Tobias, because he had no pulse when they got to him and they had to revive him.

Tobias, a retired computer programmer, said he doesn’t remember much else about Saturday’s water rescue. But between that, the bicycle crash and his cancer diagnosis which initially inspired him and his wife, Joyce, to cycle around the country, he’s pretty lucky.

“If I was a cat, I would still have about three lives left,” said Tobias, who was released from the hospital Tuesday, with a deep chuckle.

A Quantico spokesman said his two rescuers are going to be recognized at a Sept. 1 ceremony.

Denton, a nine-year veteran of the department, has received three other lifesaving awards. Seablom is the recipient of one lifesaving award.

As for Saturday’s rescue, Denton said: “We didn’t give up. We just did what we had to do. . . . I was not going to let him go.”