Officials now say it was arson.
The flames broke out around 5:30 a.m. in the 700 block of Cedar Avenue in Croydon.
Video from Chopper 6 shows thick smoke coming from the three-story home.
Officials say dangerous conditions inside the home forced firefighters to evacuate, but before the order was given, a firefighter fell down a set of steps.
Action News is working to get an update on his condition.