The fire broke out around 5:30 p.m. Sunday at St. Leo the Great Roman Catholic Church near Unruh Ave and Keystone Street.
Heavy smoke billowed into the sky as flames tore through the vacant property that was built in 1884.
Suzanne McErlain Vrana captured video of the flames shooting through the church's roof as she was traveling south on I-95.
The blaze reached two alarms before it was brought under control just after 7 p.m.
St. Leo's merged with Our Lady of Consolation in 2013. The church closed in 2019 as a place of worship and was later added to the city's historic register.
The former pastor of the church told Action News the historic structure was just sold last month and was going to be rented out to be used by religious groups.
No injuries have been reported, but the flames did spread to the former rectory right next door, displacing the family who lives there.
Dozens of neighbors gathered across the street, watching in disbelief.
"People say a church is a building, but St. Leo's was more than that to us. We made all our sacraments here," said Ann Marie Kuvik of Port Richmond.
As the church burned, people shared wedding photos from the 1960s, class photos from St. Leo's Catholic School, and childhood memories.
"Our Christmas pageants, my dad sung in the choir," said Kathy Clohessey of Tacony.
"This church, this whole school is a very big part of our childhood. It's very sad. It's heart-wrenching to see this today," said Matthew Clemons who was an altar boy at St. Leo's.
When Mary Tobin heard the news, she grabbed a St. Leo the Great prayer card that she keeps close by.
"When this happened I kind of just grabbed it and stuck it in my pocket and came down," she said.
Many of Tobin's family members were involved at St. Leo's.
"It hurts my heart, especially on Mother's Day. Both my parents are deceased, so to see this, it kind of tugs at your heart, you know?" said Tobin.
The Archdiocese of Philadelphia said while the church had not been used for some time, it will assist in the aftermath.
"The Archdiocese is working to assist parish leadership as it navigates this challenge and what relief will be available through insurance is to be determined in the coming days," said Ken Gavin, spokesperson for the archdiocese.
There is no immediate word on what sparked the fire.