Police will continue with their investigations into an incident where a high school student was seriously injured as the result of an altercation in the grounds of a high school at Mullumbimby yesterday.

About 11.15am police and emergency services responded to reports of an incident at the school.

A male Year 9 student was taken to Mullumbimby Hospital suffering a head injury.

The 15-year-old local boy remains in a critical condition.

Detectives from Tweed Byron Local Area Command, with the assistance of the forensic services group, are investigating the circumstances surrounding the incident.

Police have urged anyone with information about the incident to contact Tweed Heads Police on (07) 5536 0999 or Crime Stoppers on 1 800 333 000.