Fire crews from Glen Eden and Henderson arrived to find two people trapped in one car and a third in the other, Fire and Emergency northern shift manager Ryan Geen said.
They used rescue machinery, known as the jaws of life, to cut open both cars and free the trio.
Hato Hone St John attended the crash at 11.12pm and took three patients to North Shore Hospital - one in a critical condition and two in moderate condition.
Great North Rd was closed by emergency services between Awaroa Rd and Glenview Rd.
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