Even decades after his death, the Rev. Dr. Martin Luther King, Jr. may be setting fanatics on edge as a result of his revolutionary role in the Civil Rights Movement.

An incident Monday involving a bomb planted on the route of a Martin Luther King Day parade in Spokane, Washington appears to have been racially motivated, according to the FBI and the city's mayor.

"The confluence of the holiday, the march and the device is inescapable," Frank Harrill, an FBI special agent in Spokane, told The Associated Press, "but we are not at the point where we can draw any particular motive."

He said the concealed device was found -- and successfully defused -- by city officials just one hour before the parade, which implied it was racially motivated. Spokane has a history of crimes linked to white supremacists.

Mary Verner, the mayor of Spokane, did not act as if the day bore no relevance to the act.

"I was struck that on a day when we celebrate Dr. King, a champion of non-violence, we were faced with a significant violent threat," she told AP. "This is unacceptable in our community, or any community."

Monday was a federal holiday slated for the 81st birthday of Dr. King, the civil rights hero and Nobel Peace Prize winner who was assassinated at the age of 39.

An FBI statement after the incident described it as "domestic terrorism," warning that the device could have killed multiple people.

"Suffice it to say it was of grave concern," Harrill told NBC News.