In an alarming twist to an already concerning story, creepy clowns –one wielding a sword – have now been sighted in New Jersey, authorities say.
After four sightings in two days, police are urging people to remain calm and to use their common sense, reports NJ.com.
"We don't need a society living in fear," Philipsburg police captain Robin Stettner, said on Tuesday.
On Monday evening, a jester was seen running after a child while holding "some kind of sword". Shortly afterwards, a truck was spotted with "multiple clowns hanging out the windows," authorities have advised.
And, in a particularly scary incident, three people dressed as clowns reportedly chased a group of children near their school in Northampton County.
It comes after people in clown makeup were sighted in South Carolina – terrorising both adults and children - and trying to lure kids into the woods.
Clowns have also been seen in Alabama, Georgia, Maryland, and Pennsylvania.
At least one death has already been linked to the clown sightings. On Sunday, in Reading, Pennsylvania, a 16-year-old boy was fatally stabbed after a confrontation, which may have been provoked by someone wearing a clown mask, The Associated Press reports.
Police have told parents to speak to their children about walking in groups and to notify authorities of any suspicious behaviour.
"You see somebody in a clown mask, don't go talk to them," Stettner said, highlighting that increased sightings may be a result of "copy-catting".
A prior theory, that the clowns were part of a publicity stunt for a horror film, 31, has not been confirmed.
No arrests have been made.
In an article for The Conversation, psychologist Frank McAndrew, examines the psychology behind the creepiness of clowns.
Why do we find them so unsettling?
McAndrew and his colleagues conducted a study – the first of its kind – into creepiness. When they analysed the results, the team found that people tend to find males creepier than females (McAndrew highlights that most clowns are male), that unpredictability also ups the creepiness factor as well as unusual patterns of eye contact.
When the 1,341 participants were asked to rate the creepiness of different jobs, have a guess which job came out on top.
'The results were consistent with my theory that getting "creeped out" is a response to the ambiguity of threat and that it is only when we are confronted with uncertainty about threat that we get the chills,' writes McAndrew.
Canadian psychologist Rami Nader studies coulrophobia – the irrational fear of clowns. Nader believes that clowns set off our creep alarms because they wear make up and disguises, which hide their identities and their feelings.
"This is perfectly consistent with my hypothesis that it is the inherent ambiguity surrounding clowns that make them creepy," writes McAndrew. "They seem to be happy, but are they really?"
Clowns, he says, are also mischievous – causing people to be "on guard".
"People interacting with a clown during one of his routines never know if they are about to get a pie in the face or be the victim of some other humiliating prank," he explains. "The highly unusual physical characteristics of the clown (the wig, the big red nose, the makeup, the odd clothing) only magnify the uncertainty of what the clown might do next."