Police officers are now appealing for help to identify the two masked men (pictured) who rode around Arnold town centre on a moped wielding a knife.
They chased a 17-year-old boy and attempted to attack him with the knife on Front Street at around 3.30pm yesterday.
No-one was hurt but officers have released an image of two men they want to trace and are appealing for help to track them down.
Detective Inspector Kim Binns, who is leading the investigation, said: "Clearly this behaviour is appalling and I am asking for people's assistance in identifying those involved. The men in the image were wearing Hallowe'en-style face masks so I would ask people to look instead at their distinctive clothing and see if they recognise who they are.
"The man riding the moped is white and was wearing a grey, black and white combat-style Nike matching sports top and trousers and a rucksack with white straps.
"The pillion rider was a black man wearing a black Parka-style coat with a fur-lined hood. They were riding a red moped.
"If you think you recognise them, the bike involved or know the location of the bike, please get in touch. We are really keen to get their names as soon as possible so we get them in custody because we cannot accept people riding round a main high street in broad daylight brandishing a knife.
"We are making a number of enquiries, including CCTV, and officers are speaking to people as they carry out increased patrols in the area. If you know, or suspect who is responsible, please call us on 101, quoting incident number 565 of 14 November 2018. Anyone who wants to give information and remain anonymous can do so through Crimestoppers on 0800 555 111."