The fire was reported around 9:15 a.m. Friday at the popular Philadelphia cheesesteak shop on the 400 block of South Street.
Chopper 6 over fire at Jim's Steaks on South Street
The fire reached two alarms before it was brought under control. Officials say it was a difficult battle because the flames were moving through the heating and air conditioning system.
Christina Lawlor was in the building Friday morning, opening Jim's Steaks for the day.
"I knew it when I walked in (Friday) morning something wasn't right because it was too hot," she said.
"I started smelling something. It smelled electrical, you know you can smell that," she continued. "So I'm like, 'something's not right.' We looked up and saw smoke coming down from where the walk-in is and it was smoke pouring down."
In all, the fire department says more than 125 personnel responded to the scene, along with nearly 60 vehicles.
As the cleanup effort continues, Jim's Steaks shared a newly created GoFundMe page to help employees who are now without a job.
"Thank you for the outpouring of love in light of the fire that gutted our shop on Friday. We will rebuild. Insurance will cover sticks and bricks. However, it won't cover the lost income for our amazing crew for the months and months we will be closed. Please consider a donation to supplement all our other efforts to keep them whole during this devastating setback," said the business.
No injuries were reported in the fire.
An official cause of the blaze has not been determined.
Jim's Steaks South St. just celebrated its 46th year in the beginning of July, opening its doors for the first time in 1976.