A head-on smash on State Highway 10 was caused by an alleged drink-driver parking in the middle of the lane on the wrong side of the road at a blind corner.
The crash occurred on Kaeo Hill, between Kaeo township and the Matauri Bay turnoff, just before 10pm on Thursday.
One of the drivers had to be cut out of the wreckage by firefighters from the Kerikeri and Kaeo brigades, with that car later bursting into flames while on the back of a tow truck.
Firefighters also closed the road to allow an investigator from the police Serious Crash Unit to examine the scene and the Northland Electricity Helicopter to land on the highway.
Both the suspected drink-driver and the man in the other car, a night-shift manager on his way to work, were airlifted to Whangarei Hospital.
Sergeant Haydn Korach, of Mid North police, said the offending driver had pulled on to the right-hand side of the road and parked in the middle of the lane when the other vehicle came around a blind corner.
He had been on his way home from a work function and reportedly stopped to relieve himself.
Police are awaiting the result of a blood-alcohol test before laying charges.
The following evening, about 6.50pm on Friday, emergency services were called to another two-car smash, this time on SH1 near Rangiahua bridge.
In that case three people were taken to Bay of Islands Hospital by road while a fourth, who had to be cut from the wreckage by the Okaihau Fire Brigade, was flown to Whangarei by the Northland Rescue Helicopter.