The FBI's Salt Lake City division said hazardous materials crews were called to the IRS building about 35 miles north of Salt Lake City to respond to a possible threat.

Parts of the building were evacuated, and video on the Web site of KSL-TV showed two people being taken out on stretchers.

But U.S. Postal Inspection Service national spokesman Pete Rendina told The Associated Press the "matter was non-hazardous."

The FBI says some people had medical emergencies but that they did not "appear to be related to this incident."

Weber Fire District Deputy Chief Paul Sullivan told The Associated Press that the medical emergencies were coincidental to the discovery of the suspicious substance.

He said two people who already had medical issues happened to have episodes while authorities were on the scene and were treated. He said he couldn't release any additional information.

As of Monday afternoon, several emergency vehicles, including hazardous materials response trucks, had left the scene.

The building, surrounded by a fence, is in an industrial area. No signs on the building indicate it is an IRS facility.

The FBI says its investigation is ongoing and it couldn't release further details.

The IRS confirmed the incident in a statement Monday.

No additional details were available about the substance found or those taken from the building on stretchers.