Investigators have not yet gone inside the home, though the fire is under control, the law enforcement official said.
Investigators are still trying to determine the origin and cause of the fire, the law enforcement official said.
The source requested anonymity due to the sensitive nature of the ongoing investigation.
Philadelphia fire officials tweeted that they responded to a fire Wednesday morning surging from the second floor of a three-story row house that officials say proved fatal.
Philadelphia police described the address as a home converted into two apartments.
Both police and fire officials are on location, police said, and the scene is still active despite the fire being under control, the fire department said.
This is a developing story and will be updated.