Residents were evacuated from their homes in Victoria Street in Milnathort, Perth and Kinross while specialist explosives units raced to the scene.
Police said the device was thought to be an “unexploded ordnance device”.
A cordon has been set up and it evacuated residents are being offered temporary shelter in the local community centre.
A Police Scotland spokesman said: “Officers are currently in attendance in Milnathort after what is believed to be an unexploded ordnance device was found in the Victoria Avenue area.
“A cordon remains in place while specialist teams examine the item.
“A number of properties have been evacuated as a precaution.”