SPOKANE, Wash. – An annex at the Spokane County Courthouse is back open after people were forced to evacuate following the discovery of a suspicious envelope.

Spokane Fire personnel said a woman opened an envelope and white powder came out. The situation was isolated to the third floor of the Spokane County Superior Courthouse.

Per a release, officials said the envelope was opened around 12:06 p.m. and the contents came in contact with three county employees. None required any medical treatment, officials said. The annex's third floor was locked down and a call to evacuate was made.

Hazmat teams also responded to the area.

In a later release, officials said they believe the substance to be white correction fluid -- or better known as white out.

This is the third incident where the courthouse has been evacuated for white powder in an envelope. The previous two happened in July 2016 and the courthouse was evacuated for both of those incidents as well. The FBI tested those letters and found nothing hazardous.

Authorities said though they still treat all of these instances seriously, it is still frustrating this kind of thing keeps happening.

Editor's Note: The original story stated the courthouse was evacuated for a mysterious package.