SEATTLE - Thousands of Seattle residents will be a part of an unusual bioterrorism drill this weekend and they're just now finding out about it.

Postal carriers are delivering postcards Thursday and Friday to nearly thousands residents informing them of an emergency preparedness exercise in northeast Seattle.

The boundaries: NE 145th Street to NE 60th Street, and First Avenue NE to Lake Washington.

For postal carriers in Seattle this Saturday, it will be a drill like none other: 41 of them will hit neighborhoods in the northeast part of the city delivering tens of thousands of small boxes along with some eye-popping information.

Consider it another reminder of our ever-changing world.

The unique theory is that during the event of a bioterrorism attack, a lot of people will quickly need medications to keep them from becoming sick and the U.S. Postal Service might be one of the best ways to do that.

"The Postal Service has the unique capability to reach every residence in a large geographic area within one day," said Dr. William Raub, U.S. Department of Health and Human Services.

As part of the drill, a Seattle Police officer will walk with that postal carrier, but not approach peoples' front doors.

In a real emergency, a law enforcement escort would also happen – ideally to protect the medication delivery.

The little boxes are set to be dropped off at more than 38,000 homes.

"I want to emphasize that this cardboard box is empty and there will be no medication inside the box. There will be a flyer. This is an exercise only. No need to take any action," said Dorothy Teeter, King County Public Health Director.

Officials say delivering crucial medications by mail during what would be a chaotic time would supplement other existing methods already in place. They say this weekend's exercise is to help figure out if the Postal Service can help carry some of the weight.

This exercise is happening on Saturday – a day without normal mail service due to Veteran's Day.

King County Public Health says in the event of a bioterrorism emergency, residents would be told to go to locations in their neighborhoods to pickup medication for themselves and their families.