It happened around 11:55 p.m. Friday at OpenBox Athletics in the 1900 block of Washington Avenue.
The fire ripped through the second floor of the building.
The first floor suffered smoke and water damage.
No injuries were reported.
The fire was placed under control around 12:20 a.m. Saturday.
The gym posted on its Instagram page that all Saturday outdoor classes were canceled.
Dave Garonzik, co-owner of OpenBox Athletics, says the damage inside was primarily focused on the second floor where they held yoga classes.
The gym, which just celebrated its third year in operation, had been doing virtual and outdoor classes most recently amid the city's shutdown orders.
Garonzik says they planned to reopen their doors on Monday, but now it'll likely be a few more months.
"We are opening back up 100%. We are a resilient group," said Garonzik. "We have made it through a lot this year, and we're not going to let a fire stop us from opening the space back up again.
A cause of the fire is under investigation.
OpenBox Athletics was one of the many local gyms featured in FYI Philly's 2018 Spring into Shape episode.
The City of Philadelphia is allowing gyms to reopen on Monday as it is lifting some restrictions put in place to reduce the spread of the coronavirus. OpenBox Athletics posted an Instagram message earlier this week anticipating its reopening.
Museums, outdoor sports, in-person learning for high schools, and outdoor catered events will also be able to resume.
The city will continue its current restrictions for the riskiest settings through at least January 15.
This includes restrictions on:
- Indoor dining
- Indoor gatherings and events
- Indoor organized sports