Police say they have shot an armed man who attempted to carjack two vehicles in West Auckland this afternoon.

Police responded to an unfolding incident in Henderson, closing off a key motorway overpass as rush hour begins.

Superintendent Shanan Gray, the relieving District Commander for Waitematā, said a police unit sighted a vehicle of interest on Te Atatū Rd on the Te Atatū Peninsula.

“It was signalled to stop, but failed to do so and a decision was made to pursue the vehicle west towards the Lincoln Rd off-ramp.

 “On the Lincoln Rd overbridge, the driver has got out of the vehicle with a firearm, and has unsuccessfully tried to steal two other vehicles. During this period, one of those vehicles has hit the offender.”

Police said armed officers were quickly on scene, “approaching the man and challenging him”.

“The man has not engaged with our staff and has run towards a truck and has climbed in the passenger side of the cab resulting in the truck driver exiting out the drivers door,” Gray said.

An armed man is chased before being shot by police during an incident on the Lincoln Rd overpass in Henderson.

Police said at this stage of the incident police fired shots at the offender.

A Herald reporter at the scene said there were multiple bullet holes in a truck’s windscreen.

“Staff immediately provided first aid, and he has since been taken to hospital with gun shot injuries, however these are not thought to be life threatening,” Gray said.

Police said it was an “alarming incident for motorists going about their afternoon commute and one which unfolded quickly”.

“I would like to acknowledge our staff’s quick actions to bring this incident to a swift conclusion.”

Dashcam footage showed armed police chase an armed man near the Northwestern motorway. Photo / Supplied

Police are considering charges for the offender’s actions and police will notify the Independent Police Conduct Authority.

A scene examination will be carried out, and motorists can expect delays this evening while this work is carried out.

A man in traffic just metres from the shooting told the Herald his hands were still shaking from witnessing the incident.

“He jumped out, I saw the offender trying to smash the window of a car, sort of two or three cars in front of me,” he said. “I could see him swinging something at it, which I realise now is probably his gun.”

As the offender ran past him with a gun in hand, the motorist said he quickly put his head down, trying to not make eye contact with him.

“And when I looked in the rear vision mirror, I saw the officer shooting at him, and in the meantime, his car rolled down and sort of ran into the one next to me,” he said.

Afterwards, the motorist said he realised his car was unlocked the whole time. He didn’t want to think about what might of happened if he tried to get into his vehicle.

“I’m freaked out, when I just drove off and I had to sort of stop on the side of the road,” he said.

A white truck at the scene with bullet holes in its windscreen. Photo / Hayden Woodward

A video earlier sent to the Herald from the scene shows two police officers taking cover behind patrol cars while a third officer runs towards the overpass. Emergency service sirens can be heard in the background along with what appear to be the sound of gunshots.

“F**k, guns and all boys?” The man who filmed the video said. “Oh, shots and all.”

Another witness said there was a police chase from Te Atatu Peninsula and saw a red car “all smashed up scraping on the road”.

A third witness said the smashed-up car was being chased by police before it crashed into another vehicle.

Armed police respond to an incident on Lincoln Rd.

He told the Herald the car was already damaged as it attempted to evade police.

One offender then jumped out of the crashed vehicle and attempted to carjack a nearby truck, he said.

”I did see a car, a police car, speed off with a cop driving and then a cop in the back, and it looked like they holding, like a wound, or like CPR or something in the back seat, and it sped, like, quickly off towards the hospital,” the witness said.

Armed police at the Lincoln Rd incident in Henderson. Photo / Dean Purcell

Police investigating the scene at the Lincoln Rd motorway overpass. Photo / Dean Purcell

He said he had “clearly heard” gunshots moments before he saw the police car speed off.

Another witness said, “police are out in force with the big guns” on the Lincoln Rd Northwestern Motorway overpass bridge.

Waka Kotahi NZTA said in an update at 4.05pm, the Lincoln Rd off-ramp northbound is open but the right-hand turn onto Lincoln Rd overbridge is closed.

The left-hand turn is open, while the Lincoln Rd off-ramp southbound is closed.

A witness at the scene said traffic coming from the west was “completely gridlocked” as there was no access to Lincoln Rd. Traffic was being diverted to Te Atatu.

Traffic is backing up this evening on the Auckland's motorway network. Photo / Google

Police have closed the Lincoln Rd off-ramp. Auckland Transport and bus services were impacted and detours were likely.

Another witness said police were approaching a white truck on the overpass.

The police Eagle helicopter is circling the area.

“Motorists can expect delays and are advised to avoid the area if possible,” a police spokesman said.