Mr Fagan said police were looking for a large, green American style vehicle and another vehicle towing a large boat heading southbound on SH1 at the time of the crash.
Police would also like to speak to anyone who saw the crash or a vehicle being towed by another vehicle on SH1 between Kawakawa and Hukerenui.
Mr Fagan said police extended their deepest condolences to the families of those who died.
The crash was a reminder to motorists to take more care, especially when towing.
"The maximum speed you can tow another vehicle without a rigid towing system, for example with a rope or a strop, is 50 km/h."
"Motorists are still taking risks with their lives, the lives of their passengers and other motorists. Until the motoring public see road safety as their responsibility as well then we will continue to have tragic crashes where poor decision making has resulted in unnecessary death or serious injury."
Police are still contacting the next of kin of the deceased.
Anyone with information on yesterday's fatal crash can contact Whangarei police on 09 430 4500.