N Portland warehouse fire started underneath structure

The building at 1300 N River Road was completely engulfed

A 3rd-alarm fire destroyed a warehouse that spanned 2 city blocks in North Portland, May 15, 2017. (KOIN)

PORTLAND, Ore. (KOIN) — A fire that destroyed a North Portland warehouse started under the structure, and investigators are working to determine what caused it.

Fire destroyed a North Portland warehouse, May 14 2017. (KOIN)

Reports of the fire at at 1300 N River Road came in Sunday just before 10 p.m. The warehouse was completely engulfed in flames when firefighters arrived.

The huge blaze lit up the sky and sent smoke billowing through the downtown area. The Fremont Bridge and I-405 were closed in all directions between I-5 and US-30, but traffic was back to normal around 4:30 a.m.

Dozens of firefighters have spent hours working to put the flames out. Portland Fire & Rescue says it may take until Tuesday for the flames to be fully extinguished.

Firefighters said their biggest challenge was related to the contents of the warehouse, including things like carpet pads and other synthetic products that burned easily. There were also cars, RVs and boats inside the building.

An RV near the warehouse was completely destroyed in the fire. The American Red Cross Cascades Region said it was assisting 4 adults who were staying in the RV.

People familiar with the area say there is a homeless camp underneath the building along the Willamette River. Officials said the fire started underneath the building, and that witnesses recently reported warming and cooking fires in the area.

Anyone with information regarding the fire should call 503.823.4636.

KOIN 6 News will have more information as it becomes available.