SPOKANE -- The downtown post office was evacuated around 9:30 a.m. this morning after a report of a threatening letter.

KREM 2

Spokane hazardous material crews responded to a report of a foreign substance in a letter sent to the downtown post office.

A foreign substance was found in the package prompting the evacuation.

The letter - which had stains of blood on it - tested negative and employees returned to work just after the noon hour.

The substance turned out to be an antacid. Authorities say the letter was sent from Florida by a federal inmate who has a previous history of such behavior.