The call came in around 5:30 p.m. Wednesday for heavy flames showing on the 400 block of Leopard Road.
The fire reached two alarms before it was brought under control.
"A passerby was driving by, they saw fire coming out of the windows, so they called 911," said Berwyn Fire Chief Justin Brundage.
Crews battle 2-alarm blaze in Berwyn, Chester County
"The fire was in between the walls and also the floors, so there were a lot of void spaces. It's an older structure...Crews had to do a lot of manual labor, opening things up to get in and find all of the hidden hotspots," added Brundage.
Many were concerned for a woman they said lived at the residence.
"Apparently a good Samaritan saw her trying to get in the house, grabbed her and pulled her back. Then the cops and firefighters came and started to work on the fire," said Luke Attanasi, of Berwyn.
According to fire officials, the woman was not found at the scene and no one else was found inside the fire-ravaged home.
"We did a primary search and a secondary search, (we) didn't find anybody in the home. I don't know where the homeowner is, still trying to figure that out," said Brundage.
Online records indicate the home was built in the 1900s and last sold in 2016 for nearly $900,000.
A sign out front reads "coming soon."
Neighbors say the owners had been renovating the property and were preparing to sell.
"They worked on that house for probably about a year -- a total redo of that house," said Scott Cappelli, of Berwyn.
No injuries were reported.
The cause of the fire remains under investigation.