All three injured people were from the same car. Two of the people in the car were initially trapped and were freed by firefighters.
Senior Constable Paul Gunner said a vehicle heading towards Katikati tried to make a u-turn across the highway and collided with a car which was heading in the same direction.
The first car spun across the main road, smashed through a Seeka fence and crashed into two parked cars in the Seeka cool store car park.