Portland Ore – Investigators believe the massive 4-alarm fire in Northeast Portland on Monday was intentionally set.

Officials have not identified exactly what started it, but believe it was a human cause. They are looking at an “area of interest” northwest of the burn zone on 82nd Avenue.

Investigator Lt. Jason Anderson said they are “all hands on deck” collecting witness statements and data from the scene.

Fire Chief Sara Boone said it was a “tremendous effort” on the part of firefighters, police and other agencies to get this fire under control. The heat, wind and low humidity Monday made it a difficult battle.