( CNN ) -- Fire engulfed five luxury homes Monday morning at a subdivision north of Seattle in what could be a case of ecoterrorism , officials said . Firefighters attack blazes at luxury homes Monday in suburban Seattle , Washington . A sign with the letters `` ELF '' was found at the scene of the fires in the `` Street of Dreams '' development in Woodinville , Washington , said Chief Rick Eastman of Snohomish County Fire District No . 7 . Eastman did not say if the sign is believed to be from the Earth Liberation Front , which the FBI has called an ecoterrorist group . `` Built green ? Nope black ! '' the sign reads , according to an image from CNN affiliate KING-TV in Seattle . The sign calls the homes `` McMansions . '' Watch why ELF is so elusive » . John Heller , president of Seattle Street of Dreams model luxury home development , said he had spoken to the fire chief and was told that the fires were suspicious . Watch fires burn luxury homes » . `` My understanding is that it was an act of terror , '' Heller said . The FBI said the fires are being investigated as an act of domestic terrorism . Heller said he was out of town on business and was rushing back to see what was left of the development . He said it was a new subdivision that featured luxury homes priced at $ 2 million . Video footage showed large grayish white plumes of smoke billowing in the air and firefighters trying to contain blazes in large homes in a heavily wooded area . Eastman said there had been no injuries and there were no suspects . He told KING-TV that police and agents of the federal Bureau of Alcohol , Tobacco , Firearms and Explosives were investigating . Seattle 's Street of Dreams is `` the most popular and highest attended single site luxury home and garden tour in the U.S. , '' according to the event 's Web site . According to the FBI , the Earth Liberation Front claimed responsibility for burning five townhomes under construction on November 20 , 2005 , in Hagerstown , Maryland . Fire officials investigating the scene determined that kerosene was used as the accelerant in the arson , the FBI said . Last year , 10 people , including self-proclaimed members of the ELF and members of another organization called the Animal Liberation Front , were convicted for a string of arson fires that totaled more than $ 40 million in damage , according to an August statement by the U.S. Justice Department . At that time , the court case was called the `` largest ecoterrorism case in U.S. history , '' according to the statement . Three others charged in the case are at large and considered international fugitives by the Justice Department . E-mail to a friend .
NEW : FBI investigating as act of domestic terrorism . Sign reading `` ELF '' found at site of fires , fire chief says . Comment: