Hundreds of terrified children are flooding Childline with calls about the killer clown craze sweeping Britain.
Figures show that in just one week the charity was contacted 120 times by kids alarmed by strangers in scary clown costumes.
A quarter of calls came from under 11s and over a third from 12 to 15-year-olds.
Worst-hit are Birmingham, Manchester and Nottingham.
But there have been reports from all over the UK of clowns armed with knives or baseball bats lurking in bushes, chasing children and targeting schools.
Childline head John Cameron called for calm in the run-up to Halloween.
He said: “There’s a worrying trend of dressing up not to entertain but to behave in a very scary and threatening way.
“Parents need to say to older children: “If you decide to dress like that at Halloween remember you have a responsibility not to be threatening.”
The National Police Chiefs’ Council said: “Frightening or threatening others may be enough to warrant public order criminal offences.”
A 10-year-old boy in Plymouth was threatened by a clown who jumped out of a bush carrying a hammer.
In Workington, Cumbria, a clown brandishing an axe chased an 11-year-old girl.
Children have also been targeted online. In Cumbria a 13-year-old boy was arrested after a girl, also 13, received Instagram messages from a killer clown threatening to cut her throat and rape her.
The NSPCC has urged children to talk to parents or teachers or call police or Childline if they feel threatened.
It also advised them to block and report abusive messages from people posing as clowns on social media.
Kent Police reported 59 clown-related incidents between October 7 and 10.
Thames Valley Police had 14 in 24 hours at the weekend and South Yorkshire Police received 61 reports in 20 days, including two of clowns with knives.
On Tuesday armed officers arrested a suspect wearing a clown mask and carrying a fake gun in Hillingdon, West London, about five miles from Heathrow.
On Saturday night a student dressed as a clown sparked terror by running through a university campus at Uxbridge, West London, with a chainsaw from B&Q.
The 19-year-old, who gave his name only as Kenny, later apologised, saying he was “only chasing his friends” at Brunel University to make a YouTube video.
It’s unclear what sparked the craze which began in the US this summer and quickly spread to Canada and Australia before reaching the UK.
Some say it is inspired by Pennywise, the demonic spirit who preys on children in Stephen King’s 1986 novel It.
Tim Curry played the part in the 1990 TV mini-series.
