In November last year, the police received an alarm about an assault at Andersberg in Halmstad.
But when they arrived at the scene, a group of masked people rushed towards the patrol and they had to take shelter in a police car instead of fighting the law.
The group, which shouted derogatory words, must have consisted of 15-20 people.
The 17-year-old is considered to have been the driving force at the incident and is sentenced to youth care.
The alarm call about assault, which led the police to the scene, turned out to be a false alarm.