Police are hunting for a so-called 'Killer Clown' who followed a group of children to school.
Durham Police said the four children were unhurt, but distressed following the incident this morning.
The children, aged between eleven and twelve years old, were walking to The Hermitage Academy in Chester-Le-Street at about 8.40am when a man dressed as a clown jumped out on them and followed them towards the school.
The man was wearing grey tracksuit bottoms, red shoes, a multi-coloured top and was described as wearing a mask as well as having his face painted. He was also carrying a knife.
Neighbourhood Sergeant Mel Sutherland, said: "The children arrived at school understandably upset and distressed by this incident and we are currently trying to locate this man. My officers will be on patrol outside the school at home time this afternoon to offer reassurance to children and parents.
"We believe this to be part of a much larger prank which is currently sweeping across the USA and parts of the UK. It is very alarming he was carrying a knife however we do not think he intended to harm the children and as far as we are aware, this is part of the prank.
"There are currently several social media accounts dedicated to this 'Killer Clown' craze and we are also looking into those and who is using them.
"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."
Anyone with information regarding this man's whereabouts or any witnesses to the incident are asked to call police on 101 quoting incident 98 of Friday 7th October.