Postal workers deal with a very high-stress job, which is how the phrase "going postal" was coined. In this case the employee went "postal" with a grenade in Baxter.

The U.S. Postal Annex in Baxter, MN called the police yesterday about Robert Menth, a U.S.P.S. employee, who was threatening other workers. Police located Menth while on his mail route, where he told them that he had a grenade on him, but that it was a "dummy" grenade.

Police closed part of Highway 25 around the vehicle and Crow Wing County bomb squad was called in to investigate the grenade...which was found to be inoperative.

Menth was arrested and taken to county jail.

Source: KSTP