The fire started Thursday evening when a portion of the roof gave way and landed in a molten metal casting operation, according to Joe Meinecke with the Tacoma Fire Department.
Everyone from the foundry is accounted for and there are no reports of injuries, but Meinecke said the building's structural instability kept firefighters from entering the building.
Instead, firefighters used a defensive strategy and let the fire burn in a roughly 50-by-50 foot area inside the building.
The fire had smoldered through much of the night, then flared up again just after 5 a.m. Friday, prompting additional fire trucks to return to the scene. Firefighters had the challenge of trying to contain the fire using the least amount of water possible to mitigate risk of a steam explosion from putting water on molten metal, officials said.
The fire was back under control about an hour later.
Thursday's fire was the third major disaster to hit the foundry in just over a decade.
In October 2007, several people were injured and a 64-year old truck driver was killed in a massive propane explosion at the foundry. That explosion shot a huge ball of fire at least 500 feet into sky and shut down several nearby roadways.
An August 2002 fire did $750,000 damage and completely destroyed the foundry's maintenance shop.
The foundry, which traces its history back to 1899 when the company made iron castings for the Northwest logging industry, is near the intersection of I-5 and Highway 16.
It's unclear what caused the roof to collapse. A crane will be brought in Friday to remove part of the roof.