Flames shot out of St. Leo's Church in Tacony as firefighters arrived around 5:15 p.m.
More than 100 firefighters, medics and chiefs responded to the 2-alarm blaze at the vacant building, the Philadelphia Fire Department said.
Several people were displaced from neighboring buildings, which also sustained damage.
The fire was under control after approximately 2 hours, authorities said.
The cause is under investigation by the Fire Marshal's Office.
Built in the 1890s, the church merged with Our Lady of Consolation in 2013, records show. St. Leo's closed in 2019 and was added to Philadelphia's historic register.
The building had recently been sold and was intended to be rented out for use by religious groups, 6abc reports.
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