The Philadelphia Fire Department confirms the fire is at Philadelphia Energy Solutions in south Philadelphia.
No injuries have been reported so far, according to NewSon6.
Residents and businesses east of the plant have been told to shelter in place until further notice.
Officials say this is the second fire at the refinery in a month.
The refinery produces 335,000 barrels of crude oil daily, and employs about 1,000 people, which makes the complex the largest on the US Eastern Seaboard.
The fire has been contained in the area, and nearby roads, including a major highway, have been blocked off by emergency crews.
