The three alarm fire started at about 9:30 p.m. in a two-story building near the Comcast Arena. The building's first floor plays home to the Spare Room Vintage Flea Market, while the second story is apartments.
Firefighters from Everett, Marysville and Snohomish County managed to knock down the worst of the flames using ladder trucks to dump water on the building from above, but crews expected to remain on scene well into Friday morning.
By 10:30 p.m., crews were fighting the fire from the outside because of concerns about the stability of the building.
At roughly 11 p.m., Everett Fire Marshal Eric Hicks cut power throughout the downtown area to prevent energized power lines from possibly falling around the fire scene. Providence Hospital officials were also told to switch to generator power.
Fire officials have received unconfirmed reports of someone being inside the building, but they won't be able to go inside until Friday at the earliest.
It's unclear what sparked the fire.