The fire was reported around 10:45 p.m. Monday at an old Magnetic Metals Corporation building at the intersection of 21st and Hayes streets.
The fire raged through the overnight hours, eventually climbing to six alarms before being brought under control around 3:00 a.m. Tuesday.
While Magnetic Metals still has offices and a manufacturing plant on the same site, the building that burned has been vacant for about two years, officials said. That building was described by officials as being the size of a city block.
Employees were sent home after arriving to the plant for work later Tuesday morning. They were told no one will be allowed on the premise until the fire marshal's work is completed. The plant hopes to return to its regular schedule tomorrow.
Due to possible contamination from hazardous chemicals, residents near the factory fire were being asked to stay indoors and shut their windows. Officials also say there were about 75 people evacuated as a precaution.
One elderly resident was transported to Cooper University Hospital to be checked out.
There were no other injuries reported.