The fire was reported around 8:00 a.m. at 120 E. 3rd Street in Pottstown.
Firefighters managed to rescue three people from the home. The critically injured person was one of those people.
There was no immediate word on that person's identity.
A firefighter was also injured in the fire, however the extent of injuries is not yet known.
The fire was placed under control at 9:18 a.m.
An investigation into the cause continues.