The fire service's rope rescue team is on the way to an incident on Great North Rd, in the Waterview Tunnel area, where a person is understood to have fallen from a height.
Northern Fire Communications' shift manager Jaron Phillips said just after 4pm that a dozen firefighters were on their way to the scene, including a high angle rescue team.
He referred further comment to St John Ambulance.
An ambulance spokeswoman would not give details about what happened.
She did confirm that the person was transported to hospital and treated for moderate injuries.
A Herald reporter arrived at the scene as three fire engines and one ambulance were pulling away from the side of a large green reserve off a busy stretch of Great North Road.
A large bridge cuts through the reserve, and there's a children's playground off the side, but few people were in the area at the time of the incident.