Two ambulances and a rapid response vehicle were called to the scene, the spokeswoman said.
Motorists are asked to avoid the area. Diversion routes include Poripori Rd for south and westbound motorists, or Cambridge Rd via Poripori Rd, SH36 or SH28.
A Poripori Rd resident, who spoke anonymously, said traffic was backed up and people were being diverted down his road.
"All I know is that the phone lines are down but that is nothing compared to what might have happened to the people in those cars," he said.
The resident said there had not been a serious crash that had closed the road in the area for a while.
The Serious Crash Unit has been advised.
New Zealand Transport Agency has tweeted that the road has been closed but motorists should delay their journey as the Kaimai Ranges may have to close.
