Vehicle owners are being advised to guard against thieves after two men were seen acting suspiciously in Spalding.
The pair were thought to be looking at two motorcycles at a house in Spring Gardens before being challenged by a resident at about 1.45am on Thursday.
Police describe one of the men as white, with short black hair and wearing a grey hooded jacket, but no description was given for the other man.
Both men walked off towards Sheep Market and anyone with information should call police on 101.