(CNN) A fire burned down the main office of a social justice center in Tennessee, and officials found a symbol associated with the white power movement painted in the parking lot, the organization said.

No one was injured in the blaze Friday at the Highlander Center in New Market. The center has been involved in fighting social injustice for decades, and played a role in the civil rights movement, including hosting leaders such as Martin Luther King and Rosa Parks.

"While we are physically unhurt, we are saddened about the loss of our main office," the center said in a statement. "The fire destroyed decades of historic documents, speeches, artifacts and memorabilia from movements of all kinds, including the civil rights movement."

The Jefferson County Sheriff's Office and agents from the state bomb and arson division are investigating the blaze at New Market -- about 25 miles from Knoxville.

While it did not provide specifics, the sheriff's department said it's investigating "a symbol that was painted in the parking area of the office" to determine whether it was linked to any individual or group. Jefferson County Sheriff Jeff Coffey told the Knoxville News Sentinel that the graffiti was a hashtag-like symbol used by several groups, but "not a traditional, throw-it-in-your-face symbol that you would immediately recognize."

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