Fire damaged the offices of a high-profile politically conservative think tank last weekend in Golden Valley, and a federal agency said Friday it is investigating the blaze as an act of arson.

Center of the American Experiment said in a news release Friday that the fire was detected about 2 a.m. Sunday at its headquarters located just south of Interstate 394 and east of Hwy. 169.

The think tank's spokesman, Bill Walsh, said two other conservative organizations in the same building, the Upper Midwest Law Center and Take Charge, were also targeted by what American Experiment is calling a firebombing.

"The fire is being investigated as an act of arson," said Ashlee Sherrill, spokeswoman for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. "Since it is still an ongoing investigation, we are limited what we can add for detail."

Sherrill said that other agencies assisting in the investigation include the FBI, the Golden Valley Fire Department, the State Fire Marshal and the Hennepin County Fire Investigative Team.

John Hinderaker, American Experiment's president, said in a statement issued Friday that "the fires obviously were set by someone. They targeted conservative organizations."

Hinderaker pointed out that offices in the same building for medical professionals and the Manufacturers Alliance were unscathed.

The center said the fire started outside the first floor, home to American Experiment and Take Charge, and also in the third-floor offices of the law center. The second floor was untouched by flames, the center added.

American Experiment said its staff is working remotely and looking for alternative office space as repairs are made and the arson investigation continues in the months ahead.

"This firebombing will not slow us down," Hinderaker's statement continued. "American Experiment's work for freedom is not dependent on a bricks-and-mortar location."