The plane crashed into a Raglan inlet, near the end of East Street, on Monday afternoon.

A witness has described seeing a plane doing a 'death barrell roll' before it nose dived into the muddy flats of Raglan Harbour, killing two on board.

Fire, police and ambulance responded to the reports of the light plane crash around 3.20pm on Monday, Senior Sergeant Simon Cherry said.

The two people on board died in the crash, a police statement said.

There were no other people in the plane and no injuries on the ground.

MARK TAYLOR / STUFF NZ Two people died when this plane crashed into Raglan Harbour on Monday afternoon.

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The plane went down in one of the inlets near Main Road, in a spot police described as being near the shoreline at the end of East Street.

Raglan resident Monica Schischka was out on her deck with her flatmates when the plane went down.

Schischka said the plane was flying erratically and went into a "death barrell roll" that was a "full 90 degrees".

"We saw it coming down, heading straight down like it had fully nose dived and it didn't pull up or anything and then we heard the thud."

She said it was a muted sound and there was no fire or smoke around the wreckage.

"It was like a muffled thud. It went into the ground and we went around and had a look and it was on the mud.

"You would be surprised if anyone had lived. It was that kind of a speed and from that kind of a height.

"At first I thought they were doing a trick. But they were getting so close to the ground and then you just heard it. It wasn't a trick. We were pretty sick[ened] because we kind of knew that someone's just died for sure."

Charles Riddle Witnesses said the plane plunged into mudflats before their eyes.

Police said two bodies were recovered from the crash on Monday evening.

Police were working to identify them and let their next of kin know, a statement from Waikato Western Area Commander Inspector Andrew Mortimore said.

Several witnesses had already been spoken to, and the plane was handed into the care of the Civil Aviation Authority.

MARK TAYLOR/STUFF Two bodies were recovered from the crashed plane on Wednesday evening.

Tom Malpass lives within view of the crash site, but was picking someone up from the bus stop at the time. For him, sirens were the first sign something was wrong.

He saw the plane when he got back to his house, which overlooks Kaitoke Creek.

"I thought I would have heard it ... even the engine," he said. "If you look at it, it's hard to tell how it ended up there."

He was puzzled by the lack of marks in the mud around where the plane landed, for example.

From his house, he could see neighbours, emergency services, and local doctors trying to help. The Coastguard turned up on jet skis, he said, and surf lifesavers brought a boat around.

"It's obviously sad. It's sad at this time of year."

SUPPLIED A view of the crash taken from Roberston Road.

Raglan man Ken Hansen heard the plane fly over as he was working near Manukau Road.

"It sounded pretty all right," he said.

He thought it was a top dresser, and started to wonder if it had crashed when he heard "a whole heap" of sirens.

Another resident who lives near the inlet heard the crash.

"It just sounded like a huge impact and I immediately thought of the road," said the woman, who did not want to give her name.

She went up to Main Road and didn't notice anything - until she turned back towards the mudflats and saw the plane. As she rang 111, she heard sirens approaching and saw locals driving in through the paddocks to try to help.

Local GPs also arrived to offer help, she said.

It's a difficult spot to get to, she said, and emergency services came in from several angles with a prompt and efficient response.

"It's terribly sad."

Light planes fly over the area reasonably often in summer, she said.

MARK TAYLOR/STUFF Emergency services responded to the crash at 3.30pm.

Another eyewitness said the plane was flying around when suddenly it "dropped out of the sky".

The plane crashed into an inlet which was at low tide and very muddy.

Another witness, who saw the aftermath, said residents who lived nearby rushed to the estuary to try and help.

But as soon as they reached the scene they realised there was nothing they could do to help those on board.

She said the ambulance had now left the scene and a tarpaulin had been placed over the plane which was sitting on the mudflats.

Police said the Civil Aviation Authority had been notified about the fatal crash.

By 6.15pm, the rising tide had come in past the plane, leaving it sitting in water.

MARK TAYLOR/STUFF Emergency services approached from several directions to get to the hard-to-reach crash site.

A look back at Raglan plane crashes:

Mar 30, 2013: 2degrees boss Eric Hertz and his wife Kathy died when their aircraft crashed in the sea south of Gannet Island, after the left engine failed off the Raglan coast.

December 26, 2014: A light aeroplane crashed into the sea and sank shortly after take-off from Raglan airport. Three people were on board and one was left in a critical condition.

Jun 3, 2016: A plane overshot the runway at Raglan airfield, the two passengers walked away uninjured.