HOMES TORCHEDImages: Fires Leave Smoldering Ruins

Fire marshals and federal agents are investigating at the Storm Lake Heights development near Snohomish, where they say something suspicious has been found.

Crime tape has been stretched around a new house at the development and officials aren't saying what brought them there this morning. Video: New, Failed Apparent Arson Attempt

Officials are investigating a connection to Tuesday's developments and possible eco-terrorism: bottles of gasoline and a threatening note found at a development in the Clearview area near Maltby, and the fires that destroyed two new homes and attempts to burn two other homes in the Lobo Development near Snohomish.

The sheriff's office, the Snohomish County fire marshal, the FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were investigating.

Video: Flammable Liquid, Note Found Near Arsons

Sheriff's deputies have increased patrols at other new developments in the area.

Radical environmental groups have taken responsibility for several arson attacks in the Northwest in recent years.