One person has been seriously injured following a crash on State Highway 2, near Aongatete.
A police media spokesperson said police were called to the crash involving two cars at 1.47pm.
The crash happened on SH2 between Thompsons Track and Walker Rd.
One car is reported to be off the road and one person has suffered serious injuries, the spokesman said.
Both lanes of traffic are blocked.
A rescue helicopter has been called to the scene.
Acting head of Western Bay of Plenty road policing Sergeant Wayne Hunter said at the scene two cars had crashed head on.
He expected the road to be closed for another two hours.
A reporter at the scene said traffic was backed up at Wright Rd and flowing slowly on both lanes.
A motorist, who drove past just minutes after the crash, said she saw a car down the bank and another in the middle of the road "very smashed up".
The motorist, who wanted to remain anonymous, said she believed someone was trapped inside one of the vehicles.
The road is closed and diversions will be put in place.
Motorists are advised to expect significant delays and avoid the area if possible.