The fire broke out at approximately 3:45 p.m. at the Walnut Square Apartments, located at 201 South 13th Street.
The fire was reportedly inside a 10th floor unit of the 13-story apartment building.
Noco Kawamura, who lives on the 11th floor, heard the fire alarm, but was not overly concerned at first.
"Yesterday, there was a false fire alarm. It happens a lot in this building because I think it's getting really old," Kawamura said.
It was about five minutes later when she realized this was no false alarm.
"When I opened the door, there was smoke. I prepared a wet handkerchief and then I went through in the smoke," Kawamura said.
It took firefighters about 45 minutes to bring it under control and they were able to keep the blaze contained to the one unit on the 10th floor.
But when rescue crews first entered that apartment, they found a 60-year-old tenant inside was unconscious.
He was rushed to Thomas Jefferson University Hospital where authorities say he later died from smoking inhalation and an ensuing heart attack.
Meantime, the 130 or so occupants of the high-rise are anxious to get back inside and assess the damage.
"My cat is in there. My harp is in there and that's my livelihood. We can't go in there to make sure our animals are okay," tenant Elizabeth Bawel said.
On Wednesday night, residents on the 10th, 11th, and 12th floors were allowed back in to collect their personal items, but could not stay because of the damage.
Tenants on the ground through 9th floors were allowed back in for the night.
So far, there is no word on what sparked the fire.