Within minutes of the Monday morning fire, witnesses say the AFC located at 3600 Grant Avenue was fully engulfed.
"I'd say five minutes, less than ten minutes, it was up," AFC member Ernie Faucher said.
Video from Chopper 6 showed the magnitude of the fire that torched the local fitness center.
Action News has learned that roof work was being done when the fire broke out.
One of the workers, Kevin Kirby, tells Action News that they were doing some sort of welding work on the roof when the blow torch they were using ignited the fire, and flames quickly spread.
"It just literally went up in a matter of two minutes," Kirby said. "I'm lost for words at this point."
Kirby says they were able to get away from the fire using ladders and access points.
Eric Chernikovich, the AFC general manager, says there were close to 100 people inside, but everyone made it out safe.
Two people were taken to the hospital for treatment of smoke inhalation.
"I'm proud of people stepping up when I wasn't here," Chernikovich said.
Matt Littman, president and CEO of AFC Fitness, released the following statement Monday afternoon:
"We're extremely fortunate that our staff and members were able to swiftly and safely evacuate during the fire at our Northeast Philadelphia location on Grant Avenue this morning. The damage to the facility was severe and the Grant Avenue location will remain closed until further notice. Our team is working to accommodate displaced members and we're encouraging them to utilize our other locations in Feasterville, Jenkintown and Bala Cynwyd.
We're also working to assess the damage and determine our path forward, but can confirm at this time that we're committed to rebuilding our Northeast Philadelphia location. We truly appreciate the understanding and support of our members and the community during this difficult time."
Vic Delacruz was one of the members doing physical therapy work in the pool. He just had knee replacement surgery.
"I went out, I was shivering until one of the fire ladies handed me a blanket," Delacruz said.
Delacruz says he had no time to grab anything except a sweatshirt. He suspects his belongings inside are burned.
"I left my car keys, my wallet inside the locker. I have no way of getting home, getting my truck out of there," Delacruz said.
Fire officials say those who around the AFC were asked to stay inside until Monday evening when the shelter in place was lifted.
"If you're here, you're fine, just stay in the house, close the windows and eventually this will all go away," Philadelphia Fire Commissioner Adam Thiel said.
A hazmat team was sent inside to check on the chemicals from the pool. They gave the all-clear.
Authorities are asking residents to avoid Grant Avenue between Frankford and Academy while crews remain on the scene.
The American Red Cross responded to assess the needs of those impacted and provide assistance as needed. The Salvation Army reports their crews are providing food, beverages, care and comfort to first responders and the displaced individuals.