Halloween revellers who dress as scary clowns face arrest following a spate of threatening pranks across the UK, police warned.
In recent weeks menacing pranks inspired by the US 'killer clown' phenomenon have been reported across Britain, with a sharp increase in incidents over the weekend.
Chief Superintendent Andy Boyd, of Thames Valley Police said the force had dealt with 14 incidents in just 24 hours.
He told the Evening Standard: "Clearly we are concerned as to the nature of the behaviour of some individuals involved in this. They are putting others in fear and making people anxious.
"Some of the behaviour that is being reported would lead to arrest. We don't want to spoil the Halloween fun but we do want people to feel comfortable and safe," he said.
He warned pranksters: "You need to consider the ramifications of your actions and how you are making people feel. You may be arrested if you are putting people in fear."
The incidents have spread rapidly since police in Newcastle warned clown pranksters they risked arrest last week. In Norwich, a 30-year-old man was arrested on suspicion of public order offences after allegedly dressing as a clown and jumping out on a woman in a park on Sunday night, screaming and then chasing her. Police have increased patrols in response to such behaviour.
A masked man with a knife left a group of children aged 11 and 12 "upset and distressed" when he jumped out on them on their way to the Hermitage Academy in Chester-le-Street, County Durham on Friday.
A separate incident saw two 12-year-old boys, one wearing a clown mask and another a V for Vendetta Guy Fawkes mask, go to Howletch Lane Primary School in Peterlee to try to scare children in the playground. In Suffolk, a boy was chased by "several people dressed as clowns" in Beatty Road, Sudbury, at 8pm on Thursday, Police said.
Tom Jackson, 18, a first-year student at Leeds Beckett University, said he was "very scared" when he saw a man dressed as a clown near an underpass in Leeds at 4.30am on Friday.
A man dressed as a clown "wearing a hockey mask and a blood-stained poncho" was captured on camera in Ashton-under-Lyne, Greater Manchester, on Thursday. Police in South Wales, Gloucestershire, Bedfordshire, Essex and Northumbria have also dealt with a string of incidents.
Last week a cyclist riding in Eastbourne, East Sussex, reported seeing a person dressed as a clown jump out from a bush holding a suspected weapon. Inspector Simon Starns, of Sussex Police, said: "We are aware this is a trend that has come over from America as Halloween is approaching.
"However, while it is not an offence to dress up as a clown and prank your mates, we don't advise people to do this to strangers in the current climate of heightened security and it is an offence to carry an offensive weapon or an item which could be perceived to be a weapon.
"We will respond if someone feels threatened and the culprit could end up being arrested, and then they won't find it so funny."