One of those fires erupted around 7:10 a.m. Monday morning at a business near North Broad Street and Chew Avenue. It quickly spread and moved to two alarms.
Philadelphia Fire Commissioner Adam Thiel said it was a "deep-seated fire," saying about 100 firefighters were involved in fighting the blaze.
Officials said the inside of the building has collapsed so firefighters will have to continue their efforts from the outside of the structure.
"Obviously it's in an area where we did have a lot of unrest, but our Fire Marshals are investigating," said Thiel.
Earlier, firefighters battled a three-alarm blaze at a Rent-A-Center under the Market Frankford Line in Kensington.
On the second night of looting throughout Philadelphia, Thiel explained a helicopter first discovered the Kensington fire.
Firefighters were called to the scene on the 3000 block of Kensington Avenue, right near Allegheny Station around 12:45 a.m.
When firefighters arrived, heavy flames were shooting from the first floor of the building.
The fire continued to spread, ultimately creating a third alarm. The front of the building collapsed leaving energized wires exposed.
Officials evacuated residents from the 3000 block of Potter Street, which was directly behind the burning structure.
"There was a heavy volume of fire in this building, and with the collapses we also had burning embers travel a good distance," said Thiel. "A lot of our firefighters took up some very dangerous positions to cut this fire off and keep it from claiming this row of homes."
Thiel said these two are the biggest of the dozens of fires around the region in the last 24 to 48 hours.
"The best way to have a fire not claim a life or damage property is to not have a fire," he said. "We really hope that people will think about what they're doing."
So far there have been no injuries reported.
SEPTA is operating shuttle buses on the Market Frankford Line between Berks Station and Frankford Transportation Center in both directions due to the fire department activity.
MFL: Train service will resume at 6 a.m., however, shuttle bus service will operate between Berks Station and Frankford Transportation Center in both directions due to fire department activity.— SEPTA (@SEPTA) June 1, 2020
Investigators are still working to determine the cause of both fires.