The bus was on the Wellington to Auckand route, but the driver had not been driving the full route.
"We have another bus on its way to pick them up," Mrs Otway said.
"We're communicating with every single passenger and contacting their families to reassure them.
"We'll also be conducting our own investigation and that is already underway. Any transport company would do that."
A nursing student on her way home from placement in Taupo was one of the first on the scene.
Camberley Morton said she pulled over and ran out to help passengers.
Miss Morton said she saw a car "smushed" into the front of the bus.
"I don't know what happened to the driver but you couldn't see much of the car," she said.
"I got out and did what I could, there were a lot of people on the bus. There was petrol leaking and people had to get off the bus. They all seemed okay, a bit shaken up but nothing serious."
She said the bus was Rotorua bound and it appeared the car was heading south.
A police spokesman said the double decker bus had between 50 and 60 passengers on board.
Diversions are in place. Northbound traffic is being diverted via Te Toki Rd and southbound via Ohaaki Rd.
Earlier
Emergency services are on their way to a crash between a car and a bus on State Highway 5 near Reporoa.
Fire appliances from Rotorua and Taupo are on their way to the scene, understood to be in the area of Ohaaki Rd.
Police and ambulance are also on their way.
The crash happened around 4.50pm.
A police spokeswoman said they would advise soon if diversions would be set up.
