NASHVILLE (AP) - A suspicious substance sent to House Speaker Beth Harwell's office caused the Legislative Plaza to be closed off briefly.

A statement from Harwell says hazardous materials crews determined the substance was not hazardous.

The Commercial Appeal reports (http://bit.ly/1o7ffmw) the substance came in an envelope that legislative workers opened about 9:45 a.m. on Thursday. Hazardous materials crews cordoned off the area around the speaker's office, and five workers were medically evacuated.

Admission to the building across the street from the State Capitol was shut off, but employees who were not close to Harwell's office were allowed to remain. Employees got the all-clear to resume normal activities shortly after noon.

Harwell, a Nashville Republican, was not in the office at the time.

The investigation is ongoing.