For nearly a decade, small boats on Portland rivers have become a home of last resort for a flotilla of homeless people who sometimes refer to themselves as "hobo pirates." These floating camps, which police call "transient boats," are technically trespassing but are a symptom of the region's widespread housing shortage.

It may have been two of those residences that caught fire on the Columbia River last night.

Portland Fire & Rescue says its responders were called to the Columbia River just south of Hayden Island to extinguish "multiple boat fires" around 7 pm Monday.

"When crews arrived they found two boats," the release reads, "one described as a 30' fiberglass sailboat fully involved in fire. One was offshore anchored to a pilling or 'dolphin', the other was beached." (See footage of one of the smoldering skiffs here.)

Firefighters were unable to determine what started the fires, but say no one was aboard either vessel and no injuries were reported.

"Both boats appeared to have been used as temporary residence but were considered a complete loss according to fire investigators," the release says.

The last time Portland pirate boats caught city officials' attention was in 2016, when a man living on a floating residence fired a gun at a drone filming his boat from overhead. A Multnomah County Sheriff later determined the drone was in fact filming "a large well organized family living on the boat."