The "killer clown" craze has continued to spread across the UK with one force dealing with 14 reports in 24 hours.
Officers have been called to a string of incidents across the North East where pranksters or criminals dress as clowns try to scare innocent bystanders, and the horrific craze - which began in the USA - has also begun hitting other parts of the country.
Chief Superintendent Andy Boyd, of Thames Valley Police - whose force received the 14 calls - warned that the trend is a waste of police resources.
He said: "While we do not want to be accused of stopping people enjoying themselves, we would also ask those same people to think of the impact of their behaviour on others and themselves.
"Their actions can cause fear and anxiety to other people, this could be perceived to be intimidating and threatening which could lead to public order offences, arrest and a criminal record.
"In addition, their behaviour is causing multiple reports to our call takers and is tying up police resources which could impact on calls to other incidents.
"While we realise that reports of this kind are not restricted to the Thames Valley area, the issues of intimidation, potential arrest and waste of public resources are the same across the country and we would urge people to refrain from such activity."
His concerns were echoed by Chief Inspector Paul Staniforth from Gwent Police, which has now dealt with 18 reports including clowns "running through gardens and peering through windows, lurking around shopping centres, parks and schools and jumping from trees".
Mr Staniforth said: "The behaviour of these individuals has the potential to cause shock and panic and we are extremely concerned that this could result in somebody becoming seriously injured or unwell.
"Anyone seeking to cause distress and potential harm to anyone will be arrested. Another serious issue that people taking part in this craze are not thinking of is the impact on our resources. Every call that comes in, is taking our officers away from people that need us most."
Incidents in the North East include a masked man carrying a knife leaving 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 on Friday morning.
A separate report saw two 12-year-old boys, one wearing a clown mask and another a V for Vendetta mask, go to Howletch Lane Primary School in Peterlee to try to scare children in the playground.
But they have been occurring all across the UK.
In Suffolk, a boy "younger than a teenager" was chased by "several people dressed as clowns" in Beatty Road, Sudbury, at 8pm on Thursday, Suffolk Police said.
Terrified victims have taken to social media to document the encounters. Shaneice Price, 22, from Bloxwich, in Walsall, posted footage on Twitter of a red-hair clown who she claims tried to get into her car on Sunday.
Sporting Adidas tracksuit bottoms and a beanie hat, the clown can be seen running across the road towards the driver's door of her car.
She told reporters: "He followed me to the pub. He pointed at me and gestured that he would slit my throat, stared at me for five minutes and then left."