Opposition Leader Bill Shorten and his support team narrowly avoided a serious road crash in the NSW Hunter region on Thursday afternoon.

Mr Shorten's car was pulling over on Cessnock Road near Testers Hollow when the accident occurred, in which a car overtaking the Labor leader's convoy was involved in a head-on collision about 12.45pm.

Police had signalled for the Shorten entourage to pull over for media event as the car overtook and crashed into a car heading in the opposition direction. Mr Shorten was preparing to make an election campaign announcement about flood mitigation in the area and local journalists were at the scene.

Emergency crews helped free a 21-year-old woman and a 33-year-old woman, who had her two-year-old son in her car, from their vehicles. The younger woman suffered head injuries and was taken to John Hunter Hospital, in a stable condition.

Mr Shorten helped comfort the other woman and her son after the crash, later driving them home in his car.

Cessnock mayor Bob Pynsent and Labor candidate for the marginal NSW seat of Paterson Meryl Swanson were with Mr Shorten as the crash happened.

Councillor Pynsent said he followed the instructions of police to pull over for the media conference, with Mr Shorten's car and a police car behind him.

"Two vehicles behind us had a head on - one swerved to the other side of the road and collided with a car coming in the opposite direction," he said.

He said the road was dangerous for local drivers but he did not know why the car swerved.

"The reason we were there is it's a problem to our local government area."

"It's narrower than most of rest of the road and it has flooding issues," Councillor Pynsent said.

The road was closed following the accident and Mr Shorten cancelled a planned street walk in nearby Maitland. Labor postponed all campaign activities on Thursday afternoon.

Mr Shorten later took to Twitter to post his reflections on the accident.

"Met a brave little boy and his mum today. Days like this give us all perspective. Very glad everyone is OK - big thanks to emergency services," he said.

A spokesman for Mr Shorten said the Opposition Leader's focus has been the welfare of the occupants of both vehicles.

"His first concern is for the health and safety and wellbeing of the people involved," the spokesman said.

Ms Swanson praised Mr Shorten's response to the crash and said it was fortunate no one was seriously injured.

"He was just outstanding," she said.

"It's often when a person's true character is shown in a situation like this. He was sensitive and very reassuring."

Earlier Mr Shorten campaigned in the marginal seat of Dobell, where he announced plans to restore indexation of the Medicare benefits schedule from January 2017.

Opposition Leader Bill Shorten and his support team have narrowly avoided a serious road crash on the NSW Central Coast on Thursday afternoon.

Media, including Fairfax journalist Belinda-Jane Davis were at the scene and witnessed the crash.

Mr Shorten's car was pulling over on Cessnock Road near Testers Hollow when the accident occurred, in which a car overtaking the Labor leader's convoy was involved in a head-on collision.

Paramedics were able to free a 21-year-old woman who was trapped in her car following the crash and she was taken to John Hunter Hospital in a stable condition with minor facial injuries and pain in the knee.

Mr Shorten comforted the occupants of the other car involved in the crash, a 33-year-old woman her 2-year-old son, in the back of his official car.

The child's car seat was moved to Mr Shorten's vehicle, which has now left the scene.

a blue sedan on Cesnock Road near Testers Hollow and Mr Shorten was seen comforting a woman and child near the scene.

The woman in her 20s sustained minor facial injuries and pain in the knee and was taken to John Hunter Hospital in a stable condition.

Ambulance crews said the mother and her child were assessed at the scene and found to be uninjured.

Mr Shorten was in the region to talk to Cessnock mayor Bob Pynsent and Labor candidate for Paterson Meryl Swanson about problems with the notoriously dangerous Cessnock Road.

Mr Pynsent said he followed the instructions of the AFP officer to pull over for the media conference, with Mr Shorten's car and a police car behind him.

"Two vehicles behind us had a head on - one swerved to the other side of the road and collided with a car coming in the opposite direction," he said.

He did not know why the car swerved.

Mr Pynsent said the road was a problem and he wanted to talk to Mr Shorten about it.

"The reason we were there is it's a problem to our local government area," he said.

"It's narrower than most of rest of the road and it has flooding issues."

Mr Shorten's convoy was travelling to a media event at the time.

Police vehicles had their lights flashing as another car overtook the convoy.

Roads in the area are closed following the accident.

Mr Shorten has cancelled all campaigning for the afternoon, including a street walk event set to take place in Maitland.

A spokesman for Mr Shorten has confirmed he will not be attending any other events that afternoon and his focus was the occupants of both vehicles.

"His first concern is for the health and safety and wellbeing of the people involved," the spokesman said.

Police have established a crime scene while they investigate the circumstances surrounding the crash.

with AAP

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