The Stevens Point post office was evacuated and part of Main Street was shut down Tuesday morning after a worker reported a possible explosive device inside the building.
Police were called at about 10 a.m. The Marathon County Bomb Squad was brought in to examine the device, and a bomb-sniffing dog from Wood County helped clear the rest of the building.
At about 11:45 a.m., the bomb squad determined the device was an inert World War II-era German grenade with no explosives inside. No other explosives were found, and streets around the post office reopened around noon.
The federal postmaster and postal inspectors have taken over the investigation into how the grenade came to be at the post office.
Portage County Clerk Maria Davis said the temporary closure had no impact on Tuesday's election or on the distribution of absentee ballots.
