The alleged incident is said to have started inside the Wizards and Woozles shop in New Street and then continued outside USC on King Street.
According to the States police, the incident started at around 1.30 pm when two men were reportedly shouting at each other inside the shop.
In a statement, the police – who are appealing for information and witnesses – said: ‘One male is described as 6 ft tall, wearing a cap, with tattoos on his neck and face. The second male is described as being around 6 ft tall, wearing a blue puffa coat and carrying a blue rucksack with distinctive green straps.
‘After arguing, it is alleged that one male has produced a knife. Both men then ran away in the direction of King Street and engaged in further argument outside USC, where a punch was thrown. The two men then walked away in separate directions. One of them walked down Don Street.’
The police added: ‘This was an isolated incident where those involved were known to each other and have already been identified. Officers have already made an arrest and continue to investigate the case.’
Officers now want to speak to anyone who may have witnessed what happened or who has any information concerning the incident.
They can be contacted on 612612 or, alternatively, contact Crimestoppers anonymously on 0800 555 111 or via the online form at Crimestoppers-uk.org.