One person is dead following a two-car crash near the Awakino Gorge tunnel, bringing the Easter road toll to two.
Emergency services were called to the scene, on State Highway 3, north of New Plymouth, about 12.25pm on Monday.
A police spokesperson confirmed two cars were involved in the crash, about three kilometres south of the tunnel.
Two people received minor injuries, the spokesperson said.
Road closures are in place and significant traffic delays are expected, a New Zealand Transport Agency (NZTA) spokeswoman said.
Motorists have been asked to avoid the area.
The spokeswoman said detours will be in place shortly and asked people to follow any updates on NZTA's social media site.
Traffic stuck at the crash site has been allowed past the scene under stop/go control, although the road remains closed as a serious crash investigation is taking place, the NZTA's Facebook page said in an update posted at 3.45pm.
Among those caught in the delay was holidaymaker Glen Lovegrove, who was returning to Taranaki from Kihikihi when he hit the tail of the traffic north of the tunnel.
From his mobile phone, he said another traveller had told him there was going to be a five-hour delay.
"There's a hell of a stretch of cars," he said.
The scene was orderly although many people were turning their vehicles around, he said.
Lovegrove had also turned his vehicle, a seven-metre bus, around and was now taking an arterial road.
He said the roads in the area were very wet at the time of the crash.
The Serious Crash Unit is examining the scene.
The crash is the second fatality of Easter.
One person died following a single-vehicle crash near Huntly on Sunday night.
Emergency services were called to the crash site, near the intersection with Riverside Way, at 8.35pm.
Police confirmed one person died at the scene, while another occupant sustained minor injuries.
Seven people were killed on New Zealand's roads last Easter.