Two people are being treated for injuries caused by an explosion in a school classroom on Auckland's North Shore.

The explosion happened in a classroom at Pinehurst School in Albany.

Fire and Emergency New Zealand spokesman Colin Underdown said they sent two fire trucks to the scene shortly after 3pm.

The explosion was thought to have involved perspex, he said.

St John ambulance staff were treated two people, one for moderate injuries and another for minor injuries.

It was not known whether the patients were students or staff.

- More to come