Police are issuing warning over the "Killer Clown" craze sweeping Britain.
It follows the latest incident when a knife-wielding masked man jumped out in front of young children on their way to school on Friday morning.
The children, aged 11 and 12, were left "upset and distressed" when the man jumped out in County Durham.
People dressed as clowns have been involved in a spate of incidents across the UK.
The trend seems to have been inspired by clown-related pranks in the US, say police.
A masked clown riding a mobility scooter was caught on camera by astonished onlookers in Sheffield on Wednesday.
Local car salesmanJustin Martin Lee posted the eerie footage of the clown speeding along the the main A61 route into the city centre.
While others have mostly escaped unharmed from the "frightening" incidents, police are warning potential offenders they may be committing a Public Order Offence.
Acting Chief Inspector Darren Deex, of Essex Police, said: "We would also like to warn people who are thinking of being actively involved in this 'craze' that in doing so they may commit offences under the Public Order Act 1986 and to be more considerate of the feelings of others, especially young children and the elderly."
In Suffolk, a boy "younger than a teenager" was chased by "several people dressed as clowns" in Sudbury, Suffolk on Thursday evening, says local police.
Tom Jackson, 18, a first year student at Leeds Beckett University told how he felt "very scared" when he saw a man dressed as a clown near an underpass in Leeds at 4.30am on Friday.
Earlier this week, Northumbria Police issued an appeal and warning after a series of incidents in Newcastle involving people dressed as clowns jumping out and scaring schoolchildren.
Neighbourhood Sergeant Mel Sutherland, of Durham Police, said: "I would like to appeal directly to the people who are dressing up and carrying out these stupid acts to think seriously about what they are doing, the distress they are causing to young children is unnecessary and it needs to stop."