About 7,000 Met-Ed customers were without power Monday afternoon due to a fault on a power line.
The fault could be from a fallen tree, an equipment failure or squirrel, said company spokeswoman Kathy Seilhamer.
Crews are still working to determine the cause.
Most of the outages were around York Hospital and in Spring Garden Township, York Township and Jacobus.
As of 3:15 p.m., crews restored power to about 4,500 customers and they're working to restore the rest, Seilhamer said.
"Without knowing a cause, I can't give a specific time for full restoration, but our crews are working as quickly as possible," she said.
—Reach Candy Woodall at firstname.lastname@example.org.