A collision in Waikato, possibly caused by another vehicle, has left two women fighting for their lives.
Sergeant John Stapleford of the Waikato Highway Patrol said initial indications were that the crash, north of Ohaupo, involved more than just the two cars that collided.
"It appears the driver of a northbound silver Mitsubishi car was passing a van in the northbound lanes of SH3 when an older green Ford Falcon sedan began to follow her very closely.
"As the woman completed her passing manoeuvre she moved into the left hand lane but the driver of the Falcon then cut sharply in front of her, causing the woman to lose control of her car.
"We believe that the Mitsubishi then careered across the centreline, into the path of a southbound Honda car resulting in a collision that left both female drivers suffering critical injuries.''
Mr Stapleford said the green Ford Falcon did not stop and was seen to drive off at speed.