Firefighters were called to Planet Fitness, on the 600 block of Newark Avenue, just before 11 p.m. for a report of a fire.
Arriving crews encounter heavy smoke conditions that filled the 22,000 square foot facility, which was originally expected to open Thursday.
The blaze caused significant water and smoke damage to the gym. However, no injuries were immediately reported.
Firefighters remained at the scene late into the evening investigating circumstances surrounding the fire.
There were no injuries immediately reported.