Fire crews responded to the Cargill Chocolate Plant in Mount Joy, Lancaster County Tuesday night.
A fire broke out just after 7 p.m. at the plant, located at 200 Chocolate Avenue.
Firefighters put the fire out, but had to return to the plant around 9:30 p.m., when it flared up again.
Crews remained on the scene for several hours.
No word on the cause of the fire.