The fire broke out around 10:20 p.m. at the Kingswood Apartments located along the 200 block of Byron Place.
Chopper 6 was over the scene as flames shot through the roof.
First responders arrived before firefighters and ran into the building to rescue people. Residents said they needed that help because it was almost impossible to get out through the hallways.
"You could hear on the radio how difficult it was for them to operate in that environment," said Police Chief Thomas Nolan. "There comes a time with all first responders when you see another person in need and in jeopardy, they react. That's kind of why we all signed up to do this job."
Those first responders arrived before firefighters and ran into the building to rescue people. Residents said they needed that help because it was almost impossible to get out through the hallways.
"We opened the door and it was black smoke. The hallway was filled with black smoke. So we couldn't actually see when we open the door," said Sheldon Eggleston.
Some people jumped from their balconies to flee the fire.
"It was a very chaotic scene, fire showing, heavy smoke and many people trying to get out of the building," said Upper Merion Township Director of Public Safety.
Five police officers, one paramedic and eight residents were taken to area hospitals.
Of the eight residents that were taken to area hospitals, five were released. Three remained in the hospital as of Thursday morning.
The police officers and paramedic were treated for smoke inhalation and released.
The five officers who were treated for smoke inhalation have all been cleared to return to work.
"Who knows what they'll face tonight. They don't know that. Their families don't know but they'll still be back here tonight working hard for the community," Nolan said.
Officials said all of the residents made it out of the building.
The cause of the fire remains under investigation.
The American Red Cross is assisting displaced residents.