The car sped up, lost control after a short distance, and crashed into a rock on the opposite side of the road.
Mr Lynam said the car hit the rock with such force its engine stayed in the northbound lane while the vehicle careered back into the opposite lane.
The ambulance then rounded a corner and clipped the car in the middle of the road before coming to a stop, he said.
"The ambulance driver was shaken but uninjured in the crash while the other driver and a male passenger fled the scene, despite suffering serious injuries.''
The men were found in bushes a short time later and were airlifted Waikato Hospital with serious injuries. A female passenger suffered minor injuries.
The Waikato police serious crash unit was investigating.
Police are also awaiting the results of blood tests to determine if alcohol played a part in the crash.