Key Points:

It started with a bag snatching and ended with an innocent teenage father dead.

In the space of one hour yesterday, at least two vehicles were stolen, countless people threatened by an armed offender, a motorway became gridlocked and two innocent people were injured, one fatally.

The drama began after a bag snatch in Waitakere City shortly after 1pm.

The offender, in a stolen car, was spotted by a police patrol attending to another matter in Glen Eden at 1.08pm. The officers noticed a weapon in his vehicle, believed to be a sawn-off .22 rifle later found on the Northwestern Motorway.

An officer who attempted to stop the car found himself facing the barrel of a gun. The police gave chase as the man raced off towards New Lynn.

An elderly woman was at her niece's new Nikau St home preparing for a barbeque when she noticed the police helicopter hovering above.

The woman, who is recovering from a stroke and did not want to be identified, said they were waving at the helicopter saying, "The pretty ladies are here", when they heard a car screech down the road and pull into a neighbour's driveway.

The woman was just starting to say she hoped there weren't any criminals around when the 2m-high fence next to her started to shake.

She jumped up from her seat after seeing something out of the corner of her eye.

She initially thought it was a bag of rubbish being thrown over the fence. Instead, it was an armed man jumping into the yard.

He landed with one knee on the ground and a gun in his right hand.

"He had a gun in his hand and what went through my mind was, 'Oh, he's got a gun', but it still wasn't registering. That's when [my niece] said, 'He's got a gun', and I was off [inside]. I said, 'Girls, come in, come in'.

"I went in and said, 'Lock the doors and the windows'."

The woman's niece, who saw the man land on the ground, said he apologised before running off.

"He stood up and said, 'Sorry lady', then ran away over that fence."

She said she was initially surprised when she heard the car screech down her road and into her neighbour's driveway.

"I thought, 'What kind of people drive fast like that?' Then about five seconds later I heard my aunty's voice saying, 'Oh my god', and the man jumped over the fence."

As the women hid inside the house, the man ran through several properties.

Moments later, residents of Pine St, which runs parallel to Nikau St, were disturbed by the sound of the police helicopter and members of the armed offenders squad, who had stormed a shared driveway to about six homes.

One woman, who did not want to be identified, said she had seen a man go up the stairs to her neighbour Steven Fox's house but didn't think much of it.

Mr Fox, who is about 21 years old, is believed to have been sleeping when the offender stormed his home and demanded the keys to his Nissan Skyline at gunpoint.

The neighbour didn't see the man leave the house again but moments later she saw armed police right outside her door.

"They yelled out, 'Put your gun down and you won't get hurt'."

By this stage the man was standing outside between a car and a fence. He was pointing a gun at the police, who continued to tell him to put his weapon down.

"Then he hopped into the car, backed back and then went up straight and took off."

The neighbour said the police ran after the car but weren't able to keep up with it as it turned out of the driveway and into Pine St.

She went outside soon after and found a shaken Mr Fox being comforted by another neighbour.

"I just said to him, 'Oh, are you OK?' and he said, 'Yes'. I said to him, 'Did he point a gun at you?' and he said, 'Yes'. He was very, very shaken."

Another neighbour, who is in her 80s, fled to her bedroom in fear after seeing armed police officers outside her window.

"I peeked out the window and there were policemen crouched right under the wall.

"There was also another policeman with a big Alsatian and they were just saying, 'Put the gun down and no one will get hurt'.

"I didn't look any further because I was petrified, absolutely shaking.

"The next thing I heard was the car screeching away."

Mr Fox's father, John Fox, said he was at work in New Lynn when he heard there was a man with a gun near his home.

He rang his son, who said, 'Someone stole my car by gunpoint'. Mr Fox snr learned most of the other details from his neighbours yesterday afternoon as he waited for his shaken son to return from the police station.

Police say that when the gunman left Pine St, he drove through Avondale, Kingsland, Ponsonby and Grey Lynn before getting on to the Northwestern Motorway. Shots were fired during the chase.

It was on the motorway that pursuing officers initiated a moving blockade of the gunman's car in an attempt to protect other motorists.

Auckland City district commander Superintendent George Fraser said:"The offending vehicle came to a stop by the driver's own volition, mounted and went across the median barrier." The man got out of the car and attempted to take the van being driven by Tau Naitoko, the teenager who minutes later was shot dead.

There were a number of vehicles involved at this stage, one of which was a flat-deck truck, on which the "offender was apprehended."

Mr Fraser said Mr Naitoko was killed and the driver of the flat-deck truck was injured after also being confronted by the gunman.

"This is an absolute tragedy for the family of the dead man and, for that matter, the numerous members of public and police who were drawn into it," Mr Fraser said.

"While we are aware that several shots were fired throughout the hour or so from shortly after 1pm, we do not know who fired the fatal shot."

Several police vehicles and staff were involved over the period of the pursuit, including the air support unit, dog section and CIB.

People who found themselves in the path of the high-speed chase described a man with short dark hair driving at up to 180km/h while holding a cellphone in one hand.

Mat Kingett, 21, was on his motorbike heading along Sandringham Rd towards St Lukes about 2pm when he saw the grey Skyline speeding the other way.

"It was going quite a speed in the opposite direction. It went straight through a pedestrian crossing, with about 15 police cars following it.

"He was going for it, definitely going well over 100."

Mr Kingett said the driver looked to be in his early twenties, with short dark hair.

"He had a phone in one hand and the wheel in the other."

Pedro Marsden was at a friend's house on Great North Rd, Grey Lynn, when he heard the sirens. "I went outside and saw the car. It flew down the road about 180 ks with about 15 cars in pursuit," he said. "The bonnet was smashed up." "I thought 'stolen car' straight away."

Asked what he thought of the police pursuit, Mr Marsden said it was a shocking event.

"But if the driver had a gun, I think the police took appropriate action."

After the shooting, curious neighbours lined fences on both sides of the Northwestern Motorway at Western Springs, near the St Lukes exit.

In stark contrast to the traffic sitting gridlocked in surrounding streets, the motorway there was eerily quiet, blocked in both directions as police took photographs and combed the grass verges.

Officers cordoned off three vehicles - a white Subaru Forester car, a white Toyota van and a light truck, which the gunman is believed to have tried to hijack moments before Tau Naitoko was fatally shot.

On the other side of the motorway's median barrier, facing west, sat the silver Nissan Skyline the man stole from Steven Fox.

Only Tau Naitoko's feet, wearing dark Puma basketball boots, were visible through the sliding door of the van before police covered his body in a blue tarpaulin and moved it into a green hearse.

An eyewitness told nzherald.co.nz that he saw an armed man being taken by police from a truck on the other side of the motorway to a white van.

The witness, who did not want to be named, said he saw a Skyline smashed up and a white van parked up on the median strip.

"He had a gun in his hand and he was trying to get into the truck but by the time he got around there, three armed offenders squad members had come around the back way and more had jumped over the barrier."

Residents of streets lining the motorway reported hearing between three and five gunshots.

Chris, a neighbour who did not want to give his surname, said he was playing the video game Grand Theft Auto when he realised the gunshots he was hearing were not coming from his games console.

He told the Herald he heard three gunshots in quick succession. "They went 'pop pop pop' very quick."

Chris said it was "not good" to hear shooting so near to his back fence.

"It could have been one of us on our way home," he said. "It could have ended up in my back garden."

Another neighbour, Harry, said he heard sirens followed by a volley of up to five shots from his home on nearby Ivanhoe Rd.

Like many others who live in that street, he said, he came out to see what was happening.

"What I heard first was sirens, then I heard a car flooring it and I heard a backfire or a shot. I counted 23 cop cars at the scene."