St. Paul Fire Chief Tim Butler said a suspicious powder that forced the closing of a downtown St. Paul block and part of the City Hall and Ramsey County Courthouse Wednesday afternoon was a harmless, inert substance possibly related to yeast.

An employee in the county's Traffic Violations Bureau on the first floor opened an envelope and discovered the powdery substance about 2:15 p.m., according to Butler and St. Paul Fire Marshal Steve Zaccard.

The substance was found with a traffic ticket and payment. There was no letter or indication of a threat included, Butler said. Less than ⅛ teaspoon of powder was found.

An initial test showed it was an organic protein, and another test showed it was related to a family of substances that include both innocuous substances and toxins like anthrax and ricin, Butler said.

He added that authorities were "93 percent" sure it was related to yeast or something similar, but decided to have the Minnesota Department of Health conduct a third test. That test showed that the substance carried no safety risks.

The department is conducting a fourth test to determine what the substance was.

There was a lot of activity at the Ramsey County Courthouse after a suspicious envelope with a powder substance was found.

The violations bureau was shut down when the substance was discovered and will remain closed until the results of the final tests arrive. Butler expected it to reopen Thursday.

About 35 employees in the violations bureau were quarantined after the call came in, and the 4th Street end of the building's first floor was cordoned off. The Kellogg Boulevard entrance remained open and court proceedings continued as authorities investigated.