Taking a toy from a bear can be dangerous, especially when the toy is a mortar grenade.

Malgorzata Chodyla, spokeswoman for a zoo in Poznan, in western Poland, told The Associated Press Tuesday that a visiting Border Guard officer noticed that a female bear named Ewka was playing with something odd.

On closer look, it proved to be a rusty mortar grenade from World War II.

The bear was swiftly locked up following the discovery on Saturday, the public was barred from the area and army sappers took the explosive to a test range to detonate it safely.