Two people were injured in a three-car crash on Whangaparaoa Road in Gulf Harbour just before 4pm.
Police said people had to climb out of one car which was on its side.
Another person was injured after a two-vehicle crash on the Kaipara Coast Highway.
Police said the road was closed between Henley Road and Carol Leon Avenue in Kaukapakapa.
A second person was hurt in a serious crash involving a car and a motorcycle in Matakana, at the intersection of Matakana Road and Riverglade Lane.
Police closed Matakana Road, and asked motorists to avoid the area.
The Serious Crash Unit has been told of both crashes.
Police said roads were closed at all three crash sites, and motorists should avoid the area or be prepared for delays.