RATHDRUM, Idaho -

A suspicious package left outside a northern Idaho apartment was likely meant as an April Fools' Day joke, Rathdrum police say.

The Coeur d'Alene Press reports residents were evacuated and the Spokane Bomb Squad was called in to investigate Tuesday evening.

Writing on the outside of the package -- a shoebox taped shut -- warned it was filled with a poison that would kill anyone who opened it.

But when the bomb squad used an X-ray to look at the box's contents, it was empty.