A student has been seriously hurt after an assault at Southland Boys' High School.

A student is in Southland Hospital with serious injuries after an assault at Southland Boys' High School.

Emergency services were called to the school about 2pm on Tuesday.

School rector Simon Coe said both people involved were students at the school.

"Southland Boys' High School takes its responsibilities towards the safety of our students extremely seriously.

"We have launched our own internal inquiry and are co-operating fully with the police investigation. We will also be notifying the Ministry of Education."

Coe declined to comment further.

A St John spokeswoman said the victim was taken to hospital with serious injuries.

A police spokeswoman said a person had been arrested.