"That student has crashed into two others while a fourth was understandably quite shaken."
The car came to rest in a nearby hedge.
Mrs Grace said the students were treated for their injuries at the scene.
The 17-year-old driver of the car, who attended a different secondary school to the victims, was being spoken to by police.
"We would say that all parties involved were extremely lucky no serious injuries were suffered, which was more through extremely good luck than good management."
Mrs Grace said the teen had been driving by himself, in breach of the restrictions on his learner driver's licence.
The crash comes after a teenage driver on a learner's licence was lucky to escape without injury when his car apparently crossed the centre line and collided with a milk tanker near Hamilton yesterday morning.
"For this crash to happen the day after a collision between a milk tanker and another learner driver near Taupiri yesterday morning, there is clearly a need for focus in this area," Mrs Grace said.
The restrictions on graduated licences were in place to allow new drivers to develop their driving skills in a safe and graduated manner, she said.
"They are there not just for the safety of the newer drivers but for the safety of those other road users sharing the road with them. Clearly the incidents over the past two days show there is a lot of room for improvement.
"Motorists can expect to encounter police at any time and in any place across the Waikato checking drivers' speed, behaviour, sobriety and compliance with any restrictions to their licences."