A man wielded a knife and chainsaw when he allegedly stabbed his partner during a violent rampage on the NSW Mid North Coast which ended with the 41-year-old being shot by police.

Laura Aceglav, 28, was asleep when her on-off partner, 41-year-old Kayne Green, allegedly forced his way into her home on Heath Ave in Tuncurry, about 300km northeast of Sydney, about 6am on Friday.

Police were told Green was armed with a chainsaw and a knife when he entered the home, stabbing Aceglav multiple times in the neck before fleeing the scene in a white ute.

Officers arrived to find Aceglav seriously injured.

She was treated by paramedics before being flown to John Hunter Hospital in a serious but stable condition.

NSW Police Assistant Commissioner David Waddell said Green allegedly carjacked a white 4WD at a service station, which was later spotted by police on Stewart Parade, prompting officers to initiate a pursuit.

During the pursuit, the vehicle drove through a sportsground before crashing on the Forster Bridge.

However, when police located the crashed car at the bridge, they were told Green had carjacked another car, which was later used to ram a police car, leaving an officer with minor injuries.

A second pursuit followed, continuing into Rainbow Flat, where police allege Green drove onto a property where Aceglav’s parents live.

Still armed with a knife, Green allegedly threatened Aceglav’s mother and tried to steal her car.

He later got out of the home and confronted police. Officers allege he then ran to a neighbouring property, prompting officers to deploy a Taser multiple times.

Green allegedly charged at an officer, who discharged his firearm.

Police rendered first aid before paramedics arrived, but he could not be saved.

The residents at the affected properties were not injured, Waddell said.

Waddell said Green and Aceglav were believed to be in a de facto relationship, and police would examine Green’s domestic violence history as part of the investigation.

He was known to police, Waddell said.

Relatives of Aceglav told 7NEWS they had feared something like this would happen, describing Green as erratic, aggressive and highly controlling.

Waddell confirmed there was no ongoing risk to the public, but said the incident had a significant impact on police.

“Police go to work every day to protect the public and to save lives, unfortunately, on this occasion, we have had to use lethal force by firing of a firearm,” he said.

“But that was only after multiple attempts to stop this man using a taser, and there was a direct threat to a police officer’s life.”

A critical incident investigation has been launched and will be led by the State Crime Command’s Homicide Squad.

Anyone with information, or relevant dashcam or CCTV footage, is urged to contact police.