No explosive devices were found on-scene of a raging fire that burned several luxury show homes in a swanky development in the Seattle suburbs Monday, authorities said.

Police and the media had originally reported that several explosives were found inside the empty, unsold homes. An eco-terrorism group called Earth Liberation Front (ELF) left a banner at the scene, leading detectives to believe that the environmental group had set the blaze.

But during a Tuesday press conference, authorities backed away from reports of incendiary devices discovered inside the homes.

“There were no devices recovered,” Special Agent Kelvin Crenshaw said during the press conference. “There were five houses involved, and we still have to go into two of the residences. We are vigorously working with state and federal departments.”

Click here for photos.

Late Monday, custom home builder Grey Lundberg shook his head at the charred remains of the $2 million dream house his company built with recycled waste wood and other environmentally friendly products.

The project earned a five-star "Built Green" rating, granted by a builder's group for making construction choices that help the environment. That effort was mocked by whomever burned down the house and two others early Monday. They left behind a sign that read, "Built Green? Nope black!"

"It's just so ironic. I can't even begin to fathom that mentality," Lundberg said. "We were trying to demonstrate a better way to build out here."

The fire north of Woodinville, a rural suburb northeast of Seattle, was apparently set by the Earth Liberation Front, a loose collection of radical environmentalists that has claimed responsibility for dozens of attacks since the 1990s. The group's initials were on the sign, a sheet with red spray-painted letters.

The sheriff's office estimated that Monday's pre-dawn fires did $7 million in damage to the "Street of Dreams," a row of unoccupied, furnished luxury model homes where tens of thousands of visitors last summer eyed the latest in high-end housing, interior design and landscaping. Three homes were destroyed and two suffered minor fire or smoke damage.

The FBI was investigating the fires as a potential domestic terrorism act, said FBI spokesman Rich Kolko in Washington, D.C.

Crews removed incendiary devices found in the homes, Snohomish County District 7 Fire Chief Rick Eastman said. Later, however, Kelvin Crenshaw, special agent in charge of the Bureau of Alcohol, Tobacco and Firearms in Seattle, said there was no evidence such devices had been used.

No injuries were reported in the fires, which began before dawn in the wooded subdivision and were still smoldering by early afternoon.

The Building Industry Association of Washington and the FBI were offering a $100,000 reward for information leading to the arrest and conviction of those responsible.

"If you just stop and think about the lives that you're touching when you do something like this, it's unbelievable selfishness," Lundberg said.

Many cities have events similar to the Seattle Street of Dreams, which has been held since the 1980s. Advertising for last summer's show focused on the environmentally friendly aspects of the homes, which were smaller than some of the houses featured in years past.

The homes that burned were between 4,200 and 4,750 square feet, and were on sale at seven-figure prices.

"We are stunned by this event, and we thank God that each of the homes were unoccupied and that there were no apparent injuries," Seattle Street of Dreams Inc. President John Heller said in a news release.

The sign left behind said, "McMansions in RCDs r not green," a reference to rural cluster developments.

The homes are in a development near the headwaters of Bear Creek, which is home to endangered chinook salmon. Opponents of the development had questioned whether the luxury homes could pollute the creek and an aquifer that is a drinking water source, and whether enough was done to protect nearby wetlands.

ELF is known for trying to cause economic damage to companies or organizations it considers to be harming the environment. The group has no organized structure or leadership; typically, autonomous cells of activists take "direct actions" such as arsons and claim responsibility on behalf of ELF.

Since 1990, more than 1,200 criminal acts in the U.S. have been attributed to ELF and its sister organization, the Animal Liberation Front, said FBI spokesman Bill Carter.

Most notorious was a 2003 fire that destroyed an apartment complex near the University of California, San Diego, causing $50 million in damage.

In 2005 and 2006, federal authorities charged more than a dozen people involved in an ELF cell known as "the Family" and centered near Olympia, Wash., and Eugene, Ore. The group was responsible for at least 17 fires around the West from 1996 to 2001 — including the 1998 destruction of a lodge at the Vail ski resort in Colorado, a fire that caused $12 million in damage.

A federal jury in Tacoma was deliberating Monday in the case of another accused ELF activist. Briana Waters could face at least 35 years if convicted of helping to firebomb the University of Washington's Center for Urban Horticulture in 2001.

In another case out of Portland, Ore., environmental activist and former fugitive Tre Arrow pleaded not guilty Monday to ecoterrorism charges and was ordered held as a flight risk and public danger.

Investigators were not immediately aware of any evidence linking the fires to either criminal case, Seattle FBI agent Fred Gutt said.

Waters' lawyer, Robert Bloom, asked the judge to declare a mistrial Monday morning, citing the possibility that the fires — and their ensuing publicity — could influence the jury.

"It is inconceivable that anybody who is supporting Briana's case could have been responsible for this," Bloom said.

The judge rejected Bloom's request.

Waters, a 32-year-old violin teacher from Oakland, Calif., is accused of serving as a lookout while her friends planted the firebomb, which caused $7 million in damage. The horticulture center was targeted because the ELF activists mistakenly believed researchers there were genetically engineering trees, investigators said.

Tre Arrow is accused of helping to destroy concrete-mixing trucks at Ross Island Sand and Gravel Co. in Portland in April 2001 and of firebombing logging trucks at Schoppert Logging Co. in Eagle Creek near Mount Hood in June 2001.

ELF has timed attacks with criminal cases in the past. A few days before Jeff Luers was to be tried in 2001 on charges he torched three SUVs at a Eugene, Ore., car dealership, ELF activists hit the same dealership again. Luers was convicted.

The Associated Press contributed to this report.