Portsmouth Fire Chief Bill Raison said the call came in at 7:20, where the first responders were reporting heavy smoke and fire from the northwest section of the building.
Raison said employees reported seeing an electrical panel and things stored in the area on fire. The chief said Wednesday night it was too early to say where the fire started.
"Crews were quickly in position and made an aggressive attack," Raison said. About an hour later, the fire was out.
Raison said it fire crews did a good job getting the fire quickly under control.
"You've got molten steel, it's a foundry, so things could have been a lot worse," Raison said.
Raison said he is not aware of any damages.
Portsmouth and New Boston fire departments responded to the fire.
8 PM: A fire of undetermined origin at OSCO Industries in Portsmouth damaged the inside of the plant.
Portsmouth and New Boston Fire Departments responded to the scene Wednesday evening. OSCO President John Burke was at the scene and said he did not believe anyone was seriously injured in the blaze. No other details were immediately available.
7:45 PM: Heavy black smoke is visible billowing from the OSCO factory at 11th and Chillicothe Streets.