A threatening letter to an anti-tax group forced the partial evacuation of a downtown building Friday afternoon. Emergency crews swarmed the Plains Capital Bank building, located at 919 Congress Avenue, just after 2 pm. That's where Michael Quinn Sullivan, who is the president of Texans for Fiscal Responsibility, opened a threatening letter that contained a black powdery substance. Sullivan, whose office is on the 11th floor, says the substance got onto his pants and hands as he opened the envelope. That's when he called 911. Hazmat Crews and Austin Police responded to the scene. The entire 11th floor and several other offices in the building were evacuated. When authorities were finally able to test the powder, it turned out to be harmless. Sullivan says it's a disturbing way to send a political message.

"This is the wrong way for somebody to make a political case," says Sullivan. "We live in the freest nation on the planet where folks can have a reasonable discussion about even the greatest disagreements. You don't need to resort to this silliness."

The Austin Police Department's Homeland Defense Unit and the F.B.I. are now investigating the source of the letter. As president of an anti-tax group, Sullivan hopes whoever sent it will have to pay for the emergency response. Austin Police tell us that's a possibility.