PORTLAND, Ore. (AP) - Investigators said Thursday they were questioning three "persons of interest" in a series of vehicle arsons in southeast Portland and Milwaukie, but no charges were filed.

Thursday afternoon, police and the Metro Arson Task Force announced they arrested the three and charged them with multiple counts of arson and criminal mischief. One suspect is a minor.
     
Meanwhile, an eighth vehicle burned on Thursday morning, this time in northeast Portland.

Seven pickups or small sport utility vehicles were ignited Tuesday and Wednesday.
     
Investigators had said they were not attributing the arsons to any group or individual, although some noted that the fires came as a federal judge in Eugene began rendering sentences in arson cases across the West in the 1990s and early 2000s, starting Wednesday with Stanislas Meyerhoff.
    
 "The timing of the arsons and the court appearance of Meyerhoff has not been lost on us," Colene Domenech, a resident agent in charge of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives in Portland, told The Oregonian newspaper. But, she said, there was no evidence of a link.
     
Beth Anne Steele of the FBI said agents were helping in the investigation, "but that's only until we determine we have a real role."
     
Other officers said it was possible the arsons were aimed at getting engine parts for Honda CRVs, three of which were totaled on Tuesday.
     
Each vehicle was parked in a driveway or on the street in a residential neighborhood. None had locking gas tanks. One fire caused minor damage to a house, but no one was injured. In some cases, the vehicles were destroyed.
     
In one case, officers said, an attempt to burn a pickup largely fizzled after someone pried its gas cap, drizzled a line of gasoline down the sidewalk and ignited it.

The gas cap was burned, officers said, and the fire left a residue of burned gasoline on the side of the pickup. But the vehicle was not damaged further.
     
(Copyright 2007 by The Associated Press.  All Rights Reserved.)