WOODINVILLE, Wash. -- Investigators are hoping surveillance video taken at the scene of fires that destroyed three luxury showcase homes will lead them to those responsible for the attacks, KIRO 7 Eyewitness News reported.

Investigators spent hours on Monday sifting through the torched homes, looking for evidence in what they called a "possible case of domestic terrorism." A sign at the scene bore the initials of the Earth Liberation Front.

Damage from the "Street of Dreams" fire near Woodinville is estimated at $7 million. Three homes were destroyed and two others damaged.

Federal investigators told KIRO 7 Eyewitness News one of the homes has a video surveillance system that may hold clues about who set the fires. Investigators are also questioning real estate agents to see if anyone suspicious may have stopped by one of their open houses.

Officials from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives are holding a media briefing Tuesday morning to discuss new developments in Monday's fires.

People involved with the development said they don't understand why anyone would target homes designed to showcase eco-friendly designs.

"How can they do something like this? It's ridiculous, you know. It's the saddest thing you ever did. You destroy thousands of people's lives," said Bob Hoffman of Greater Realty.

Meanwhile, the Building Industry Association of Washington is offering a $100,000 reward for the arrest and conviction of whoever set the fires.

The president of the organization, Brad Spears, said, "While ELF used to spike trees and sabotage logging equipment, they're now burning down homes." He said it is only a matter of time before someone is hurt or killed by ELF terrorists.