Cambridgeshire Police have warned anybody who causes distress to others by getting involved in the clown craze could result in criminal prosecution.
The social media craze has seen people dress up in clown outfits and knock on windows or chase people down streets.
In some instances clowns have been reported carrying knives.
Police have sent advice to schools across the county urging anyone concerned to call 101.
Inspector Paul Rogerson, of Cambridgeshire Police, said: “Police forces across the country have been dealing with some instances of people who are dressing up as clowns in order to frighten others.
“In Cambridgeshire we have received several reports of incidents of this nature.
“While some might view this as funny, the act of frightening or threatening others may be enough to warrant public order criminal offences.
“With Halloween around the corner I’d like to take this opportunity to remind people that deliberately causing distress to another person could result in criminal prosecution.
“In the coming weeks we do not want to spoil the fun of genuine trick or treaters, however anti-social behaviour and intentionally causing distress to others will not be tolerated.”
Schools in the area have sent text messages to parents saying: “If your child informs you that they have been chased or frightened by a clown please call 999.
“If your child informs you retrospectively of an incident please also report this but by using the 101 number.”
In Whittlesey it has been reported on social media that four people were seen in Sycamore Road banging on windows before running to the car park and jumping in a red Vauxhall.
A 15-year-old girl in King’s Lynn was chased by someone wearing a clown mask, prompting police to appeal for the public’s help.
The official King’s Lynn Police account posted a tweet at the weekend: “Officers are out looking for a clown in the Gaywood area. If seen please let us know on 101. Thanks.”
Sargeant Elvidge, from King’s Lynn police, added: “We did have this problem with people dressing up as clowns and scaring people a few years ago in King’s Lynn and whilst some people may believe this is a funny prank I would like to urge people not to do this as it can cause harassment, alarm or distress.
“Deliberately jumping out or following people in this manner and trying to scare them may constitute a public order offence.
“If anyone is thinking of doing this they need to be aware that their actions may involve a police investigation and the individual getting into trouble with the police.”
In recent weeks, people on social media have reported clown sightings in Norwich, Cheshire, North Wales, Dundee, London, Manchester, Newcastle and Sheffield.
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