Four people are in hospital including one in a critical condition following a high-speed, head-on crash north of Auckland overnight.

Emergency services responded to the serious crash just before 9pm last night at the intersection of Kaipara Coast Highway (SH16) and Makarau Rd.

Emergency services at the scene of the crash on State Highway 16 north of Auckland last night. (Photo / Auckland Rescue Helicopter Trust)

Auckland Rescue Helicopter Trust spokesman Lincoln Davies said the Westpac Rescue Helicopter assisted at the crash.

Two patients in serious condition, and one in a moderate condition, were taken to hospital by St John Ambulance.

Four people were taken to hospital after the head-on crash last night. (Photo / Auckland Rescue Helicopter Trust)

The Westpac crew assisted a fourth patient, a man in his 30s with multiple injuries and in a critical condition.

He was flown to Auckland City Hospital.