One person has died following a serious single-vehicle crash in Amberley, North Canterbury.

The crash occurred when a car collided into a power pole on Lawcocks Rd, Amberley.

Emergency services were first notified about the incident at 2.25pm today.

Police confirmed the crash had turned fatal after reporting earlier today one person had sustained serious injuries.

The road is blocked and diversions are in place, police said.

Meanwhile, a child has been critically injured after a collision with a car in the West Auckland suburb of Henderson this afternoon.

The incident took place on Hindmarsh St, a police spokesman said, who confirmed the child has been transported to Starship Hospital.

"It occurred at around 3.15pm near the intersection with Bruce McLaren Rd," he said.

"Part of Hindmarsh St is currently closed while inquiries continue at the scene. The Serious Crash Unit are examining the scene."

A St John spokeswoman told the Herald one ambulance and a rapid response vehicle were sent to the scene at 3.11pm.

She said one patient was treated by staff in a critical condition.