A fast-moving four-alarm fire that destroyed a North Portland building housing a food manufacturer continued to burn Tuesday morning, as fire crews navigated the unstable building, Portland Fire and Rescue reported.

The blaze started as a grease fire around 4 p.m. Monday at Shin Shin Foods at 400 North Thompson St. By Tuesday morning, it had ravaged the entire factory, Portland Fire spokesperson Rick Graves said.

“The building will be a complete loss,” he said.

The grease fire, which sent columns of dark smoke billowing over Interstate 5, started in a hood vent, the fire bureau reported. With many flammables stored closely together within the facility, flames grew easily. All factory employees exited the building safely, and no injuries have been reported as of Tuesday morning, Graves said.

The 100-year-old structure, where Shin Shin Foods made noodles and other food products, posed safety concerns early on in the fire, according to a Portland Fire statement. Flames destroyed the roof and the exterior walls were cracked. Crews had to be aware as they worked in and around the large building that parts of it could collapse.

Nearly 100 firefighters battled the blaze, according to the fire bureau’s statement.

Getting water to the growing fire was particularly tricky, Portland Fire reported. The building is between North Interstate Avenue and I-5 in an industrial area north of the Portland Public Schools headquarters building.

At one point, 2,000 gallons of water a minute drenched the flames. Fire crews are still on the scene, putting out remaining flames and carefully going through the building, Graves said.

“We are not putting members at risk of injury to speed up our extinguishment,” Graves said.

— Sujena Soumyanath is a reporter on The Oregonian/OregonLive’s public safety team. You can reach her at 503-221-4309 or ssoumyanath@oregonian.com.