Spalding Police Station and nearby homes were evacuated after a hand grenade was brought in - only for it to be a dummy.
The fake device was brought into the police station at around 11.20am this morning (Sunday) by a member of the public.
The bomb disposal unit was called, with the device presumed to be real. The police station and homes within 100m were evacuated as a precaution.
The B1172 outside the station was also closed.
The cordon was soon lifted, however, after the Explosive Ordinance Department team examined the item and realised it was a dummy.
A Lincolnshire Police spokesperson said: "Apologies for any inconvenience, but better to be safe than sorry!"