The smoky, fast-moving fire broke out just after 9:00 a.m. and quickly went to two alarms.
The landmark building could be up to 200 years-old. The Suit Corner business has operated there for 60 years, according to the owners.
Jerry Ginsberg owns the building and his son runs the business. Ginsberg says his son told him that the fire erupted as they prepared to open for the day.
Ginsberg and a half dozen employees tried to put the fire out, but eventually had to flee for their lives.
Bob Inamdar operated the newsstand on the same corner. He soon had to scramble to safety Wednesday morning with the others.
Inamdar tells Action News, "I came out and I look at it. I see the flame coming out from the store. I say, 'What happened?' He said, 'It caught on fire.' And I say, 'Oh my God.' And then I just went back in, collect all my stuff, lock the door and get out."
The fire department says they were on the scene three minutes after they got the first call and had it under control within 90 minutes. At a critical point they shut down the water and let the roofs collapse so they could see inside to zero in on where the hotspots persisted.
Fire Department Deputy Chief Eric Fleming explained what was fueling the fire, saying, "We have no idea, besides the combustibles inside the retail store, and they might have had some storage in another portion of the building. So just the combustibles in the store."
Ben Cross lives in a next door apartment. He says, "All I know is they keep a lot of stuff in that [Suit] Corner. A lot, a lot... a lot of stuff."
One firefighter was hospitalized today for treatment of a leg injury he sustained after falling off a piece of equipment at the scene.
This fire broke out across the street from the old Shirt Corner building, which collapsed while under demolition back in mid-March.
It's been a difficult day - a difficult month - for this Old City neighborhood, and now this one corner is forever transformed.
Smoke filled the air all afternoon along Market Street between 2nd and 4th streets as the fire continued to burn at the Suit Corner store. Some of the smoke billowed right into businesses on the block.
Tom Pelkowski from SOHO PIZZA says, "One minute it's nothing - no smoke at all. The next minute you see a big billowing cloud coming down the street."
Market Street stayed shut down with no buses running along the blocks near the fire - from the moment firefighters responded right through the afternoon. For the owners of nearby stores, that meant the customers just weren't coming.
Coffee shop owner Shoyena Adiba said it's, "Terrible. I mean the whole area's been closed. Nobody could get through. 2nd Street is closed. 3rd and 4th are closed. Nothing."
It's been a rough month on this block. On March 13th, while the Shirt Corner store was being demolished, a large section came down with a crash - sending dust and debris into the street.
Michael O'Halloran owns the restaurant next door to that site. He was forced to shut down and doesn't know when he can open his restaurant due to the smoke from the fire.
"It was like this but faster. So the demolition took moments and then they cleared it up, and then they were gone. And then this - I can't believe how long it's going," O'Halloran said.
All residents except for the ones in the building are back in their homes Wednesday night.
Firefighters plan to be on the scene overnight and Thursday morning.
The fire marshal is expected to get his first look inside as he tries to figure out the cause.
Market Street remains closed between 2nd and 3rd Street around the fire scene, and SEPTA bus routes have been detoured in that area.
For the latest on SEPTA's service visit septa.org.