The Rapid Transfer building located at NW 17th and Front sustained heavy damage in the fire.
The wood framed structure of the single-story building allowed the fire to spread rapidly.
"The sky was just filled with super black, thick smoke and we heard a couple of explosions, but we don't know what it was," Angela Snyder told KATU News.
Firefighters say it is strange that there would be explosions because the warehouse was supposed to be empty and ready to be leased.
Although crews were able to keep the flames from spreading to a nearby building full of explosive chemicals, two semi-truck trailers did end up getting burned in the blaze.
No one was injured in the fire, although one of the explosions was so large that the concussion from the blast blew some of the firefighters back and also cracked a windshield on a fire truck.
Fire officials say the building itself is a total loss and firefighters will not even try to get inside until later today to begin their investigation.
