SEATTLE — Two radio station towers north of Seattle were toppled early today, with a banner left nearby bearing the initials of the Earth Liberation Front.

A FBI spokesman said authorities haven't found any evidence other individuals or groups besides the ELF were involved.

The towers were torn down because of health and environmental concerns, according to an e-mail from the North American ELF Press Office, which has represented the shadowy group in the past.

"We have to weigh our priorities, and the local ecosystem in Everett, along with the local residents, do not need additional sports news radio station towers that come at the expense of reduced property values and harmful radio waves," ELF press office spokesman Jason Crawford said in the e-mail.

The ELF is a loose collection of radical environmentalists that has claimed responsibility for dozens of attacks since the 1990s. The FBI took over as lead investigator in today's incident.

The towers apparently were taken down with a track hoe, a piece of heavy construction equipment that was already on the site, FBI agent Marty Prewett said.

The ELF's Web site featured a picture of one of the towers lying on its site with the caption "Earth Liberation Front Topples Two Radio Station Towers in Snohomish County, WA," followed by the words: "Details coming soon."