They were not simply arrested for living in an empty house.

“A home in the Parkrose Heights neighborhood has been cleared of squatters and suspects engaged in other criminal activity, leading to several arrests and seizure of drugs, guns, and stolen property,” the Portland Police Bureau said in a press release.

The home in the 220 block of Northeast 102nd Avenue had been “a significant source of disruption in the neighborhood, generating a high volume of police calls over the past year and complaints from neighbors,” PPB said.

[…]

“While he was away, the home had been taken over by multiple individuals involved in criminal activity, including a drug dealer and an individual posing as a landlord who was illegally charging people to live on the property,” police said.

It also sounds from the article like the homeowner was expecting to return home after recovering, which might not have gone well given how many weapons the squatters had.