'Clown' stabs teenager in Sweden
Police are searching for a man wearing a clown mask and a yellow jacket who stabbed a person in southern Sweden.
Police spokeswoman Ulla Brehm said there have been two similar incidents where people dressed like clowns stood outside schools and scared children.
"This is not a crime as such but very, very unpleasant," she added
Ms Brehm said the incidents are likely to have spread via social media from the United States, adding: "It is not funny when people are being scared."
She said a 19-year-old man was stabbed late on Thursday with a knife in the shoulder in Varberg, south of Goteborg.
He sustained superficial wounds and despite searches, the attacker has not been found.
Similar incidents were reported elsewhere in Sweden, Denmark and Norway - where the Ringo toy store chain decided to stop selling clown costumes in its 114 shops.
"We have done so in the wake of the recent so-called 'killer clowns' episodes," Ringo chain chief executive Gro Svendsen said.
"This is a phenomenon which we strongly oppose. Costumes and disguises should be for fun and not motivated by the desire to spread fear."
In 2013 a clown, carrying a clown teddy, was reported to be 'terrifying residents' in Northampton, England.
The clown, who remains anonymous, gained worldwide attention and saw copy-cat clowns take to the streets around the world.
The Northampton clown later took to social media to say no harm was intended and it 'just a bit of fun'.
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That same year a Carrickfergus clown turned himself in to the PSNI after detectives received reports that he was frightening local children.
The PSNI said later that they had spoken to the man and were satisfied that he had no sinister intentions and it was just a prank.
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However the clown craze saw a resurgence this summer when police in South Carolina responded to reports of 'creepy' clowns trying to lure children into woods. Since then, there have been numerous other reports and warnings from police in other US states.
Meanwhile, footage has also emerged of a mob of Penn State University students apparently on the hunt for three clowns spotted in the area.
There is now even a #IfISeeAClown hashtag trending in the US.
Coulrophobia: The fear of clowns
An irrational fear of clowns has come to be known as as coulrophobia. The prefix "coulro" comes from the ancient Greek word for "one who walks on stilts."
Symptoms include feelings of dread, increased heartbeat, sweating, nausea and anger.
A University of Sheffield study from 2008 found that out of 250 children aged four to 16 images of a clown were widely disliked. The researchers said clowns were "universally disliked by children" and that "some found them quite frightening and unknowable."
Perhaps the most famous killer clown was the child murdering monster Pennywise from the 1990 television movie IT. However the killer clown has been a regular feature of several horror films including Clownhouse, Mr Jingles and 2004's In Fear of Clowns.
The genre also includes the 1988 classic 'Killer Klowns from Outer Space', which had the tagline: "In Space No One Can Eat Ice Cream".