PENN Power says a substation in Ellwood City experienced a disruption of power.
More than three million people were without power as of Monday evening, and most of them are in and around New York City.
Some people in western Pennsylvania remain without power after strong storms pummeled the region Thursday.
A utility pole split, started a brush fire and knocked out power for 500 Penn Power customers in Butler County. It happened along Route 68 in Evans City.
Police and First Energy are offering a $1,000 reward for information in a copper theft that caused a power outage for 4,000 customers.
Multiple lightning strikes led to the massive power outages in Butler County and northern Allegheny County Tuesday night.
The people without power are apparently customers of Penn Power who live in areas including, Mars, Ross Township, Cranberry and Seven Fields.