A single-vehicle crash has closed State Highway 1 near Horeke in Northland, with one person airlifted to hospital in a serious condition.

Police were called to the scene, near Rangiahua Rd, at around 9.20am.

"Initial indications suggest there are serious injuries," a police spokesperson said.

"The serious crash unit has been advised. The road is closed, and diversions are in place. Motorists are advised to avoid the area and expect delays."

One helicopter and three ambulances were called to the scene, St John said.

A person was airlifted to Whangārei Hospital in a serious condition, according to the ambulance service.