Youngsters terrified by the sinister "killer clown" craze sweeping the UK have been turning to Childline for help.
In just one week the charity was contacted 120 times by children scared by people dressed up in frightening clown costumes.
Police have been forced to deal with a wave of clown-related incidents, and have warned that jokers or criminals using the costumes to deliberately scare people will face arrest.
A quarter of the calls to Childline about clowns came from children under 11, while more than a third came from terrified youngsters between 12 and 15.
Most calls came from young people in Birmingham, Manchester and Nottingham, the charity said.
The craze originated in America and has swept across the Atlantic. Some incidents have specifically targeted schools.
A 10-year-old boy in Plymouth was threatened by a clown who jumped out of a bush carrying a hammer, while in Workington, Cumbria, a clown brandishing an axe chased an 11-year-old girl.
Children have also been targeted online. A recent case saw a 13-year-old boy arrested for malicious communications, after a girl the same age in Kendal received Instagram messages from someone posing as a clown threatening to cut her throat and rape her.
With Hallowe'en coming up, John Cameron, head of Childline, urged people dressing up to act responsibly.
He said: "There is a worrying trend at the moment with some individuals, be they older children or adults, deliberately seeking to dress up in a way not to entertain but to behave in a very scary and threatening way.
"That's a conscious behaviour and should not be tolerated. Sometimes people don't understand the impact that can have."
Calling for parents to warn their children about the potential consequences of their actions, he said: "We need to get parents to say to older children, 'If you decide to dress up like that at Hallowe'en, remember you have a responsibility when you're running around the streets - to have fun but don't be threatening and intimidating'."
The NSPCC urged worried children to talk to parents or teachers, call police if they feel threatened in the street or contact Childline on 0800 1111 or at www.childline.org.uk.