Police believe driver error may have been a cause of the Wellington crash and are keen to hear from anyone who remembers seeing a Nissan van or a Honda before the crash at 8:40pm.
Both incidents are being investigated by the Police Serious Crash Unit.
The overnight crashes follow a head-on-collision near Palmerston North yesterday in which two people are understood to have died.
The passenger of one car, believed to be an elderly woman, was killed while the female driver and two children also in the car were seriously hurt.
The driver of the other car, an elderly man, was also seriously injured and later died, according to reports.
Two further crashes near Tauranga and Taupo claimed four lives overnight on Thursday, bringing the road toll to eight in less than 48 hours.