Still, everyone in a 3,000 foot radius of the explosion was evacuated due to fears that there would be more, and larger, blasts.
The explosion happened around 12:45 p.m. Wednesday at Scully Welding Supply at the intersection of Oak Avenue and MacDade Boulevard in Collingdale.
The fire was put our nearly five hours later.
During that time, there was concern that the flames would hit two large propane tanks filled with gas. One of the tanks holds 33,000 cubic feet of propane gas, while the other has 18,000 feet of gas.
The American Red Cross said that approximately 200 residents have been asked to leave their homes.
Delaware County Emergency Services Director Ed Truitt says dispatchers received reports of multiple explosions, which were still ongoing when firefighters arrived.
A total of four people, including a firefighter, were hurt. Their injuries did not appear to be life-threatening.
Emergency officials are waiting for company officials to provide a headcount of who was in the building, Truitt said.
Tammy Scanlon, 38, who lives a few hundred yards across the railroad tracks from Scully's Propane, heard the explosions go on for about 30 minutes.
"It sounded like a car backfired the first time. It got worse," she said. "You could feel the dishes shaking in my house. It was just one after another."
Kimberly Bench, 47, said she felt the air suck in and out of her house and looked up to see a big piece of metal hurtling skyward during the blasts.
"We heard a big explosion. Our house rattled," she said.
Butch Cook, who manages a nearby a sandwich shop, said he heard a series of explosions, each one followed by flames, for about 20 minutes.
"You would hear a bang, and then the flames would be there," the 54-year-old Cook said.
Shelters set up for evacuees
All of the evacuees are being directed to the Folcroft Fire Station at 1647 Delmar Drive for a shelter provided by the American Red Cross.
The Associated Press contributed to this report.