The bizarre ‘killer clown’ fad that began in the U.S has now spread to Ireland, Northern Ireland and parts of the UK.

The prank involves people dressing up as scary clowns with the intention to terrify or intimidate members of the public.

The BBC reports that police in Northern Ireland have said that behavior which deliberately “generates fear,” including posting threatening messages, can lead to a criminal record.

PSNI said they have received several reports of individuals posting on social media sites encouraging other to dress in clown costumes and go to schools to scare teachers and students.

Assistant Chief Constable Stephen Martin said: "I would advise anyone who may be considering posting information on social media platforms to consider what they're saying.

"Crime is crime, whether in the virtual world or the real world and there are consequences. Please don't get caught up in something that could jeopardize your future."

People dressed as clowns have been seen in Belfast, and Belfast Live reported that a grammar school in Coleraine was put into lockdown after threats from so-called ‘killer clowns’ on social media.

In Dublin, students and teachers at the Newpark School in Blackrock were reportedly terrified when a group of people dressed as creepy clowns and toting what turned out to be faux chain saws appeared on school property. It turned out that they were planning on handing out fliers for a local Halloween attraction, but the school and Gardai (Irish police) took the incident very seriously, as the clowns did not have permission to be on school property. 

One mother told the Irish Independent that her daughter was terrified.

"She told me that at least one teacher was panicking. The level of hysteria among the students was shocking. One of the sixth-year students was screaming, telling everyone to stay indoors."

In America, the hoax has at times escalated into violence, and there have been several incidents of people attacked and assaulted by people dressed as clowns.