State Highway 1 north of Auckland is closed and three people have been seriously injured, following a crash between a truck and a car.
Emergency services were called to the crash, south of Warkworth at 1.55pm.
St John said three patients had been transported to Auckland Hospital in a serious condition.
The highway is closed between Woodcocks Road and Valerie Close.
The Transport Agency is advising people travelling between Silverdale and Wellsford to use State Highway 16.
UPDATE 2:35PM— NZTA Akld & Nthlnd (@NZTAAkl) September 22, 2019
Due to a serious crash in Warkworth, SH1 is closed between Woodcocks Rd and Valerie Cl. No detour available. Please delay your journey or avoid the area, if possible. ^EHhttps://t.co/V52bJ11y11