A serious assault occurred outside the Stavern Festival around 8:42 PM, prompting a response from police and ambulance services. Five individuals were involved in the fight, and one young man sustained significant injuries and was transported to a hospital. Police have detained four young men in connection with the incident and are currently investigating the events that led to the altercation. Authorities are working at the scene to determine the precise sequence of events. The investigation is ongoing as police seek to gather more information about the fight and the individuals involved. No further details regarding the victim's condition have been released at this time.