Shortly after 22 on Saturday evening, the police were alerted to the Strandskolan in Lomma, when a young person was cut in the school yard.
The man has been taken to hospital by ambulance. Police have been told that between 20 and 30 people were at the scene when the man was cut.
Several patrols have been called in and also a police helicopter in search of one or more perpetrators.
The incident is currently classified as attempted murder, or murder.