Four helicopters and 15 ambulances were deployed to the incident, NSW Ambulance says.

The Newcastle Knights have given a brief statement about the crash, saying the club is "aware of the traffic incident that occurred this morning in Wallsend".

The statement came from Chris James, the Knights' director of football.

"Our thoughts are with everyone impacted by the incident, including those at the scene and their families," the statement says.

"As this is a matter for NSW Police, the club will not be making any further comment at this time."

Newcastle Knights fan Dylan Prior told ABC News that he witnessed the incident at Wallsend.

He was with his two young daughters and his mother, having arrived at 8:30am, with the expectation that the Knights' team bus would go by around 10am.

He said the mood was upbeat, with "everyone there, cheering and beeping".

But at around 9:30am, he said he was shocked to see the accident unfold.

"A BMW came around the corner, it was revving a bit, and it ran into a group of people," Mr Prior said.

"We've had a bit of rain here, and weather played a part in it.

"I saw some young kids go flying, and people running to help the victims.

"Everyone was yelling and hysterical, yelling at the driver.

"They were screaming for help."

Mr Prior said there was only one police officer on site, and he quickly joined the effort to help the victims.

"But I wish there had been more police around. This could have been avoided if more police were in sight," he said.

"The mood is very deflated at the moment. I can't help but think of the victims."

Newcastle Mayor Gavin Morris has told ABC News the driver of the vehicle was reportedly revving his engine before the crash.

"He was excited, he was a supporter, he was, you know, a fan, he was there for the joy of the moment as well," he said.

"Somehow, yes, he has lost control of the car."

The details of the incident are still emerging, but here is what has been confirmed:

• Fans of the Newcastle Knights had gathered along roads in Wallsend, Newcastle, to see the team off as they made their way into Sydney for the NRL grand final
• About 9.30am, a car travelling on Newcastle Link Road collided with a crowd of supporters
• Nine people have been injured, with NSW Ambulance saying one person is in a critical condition, and another is critical but stable
• All nine have been taken to John Hunter Hospital
• Emergency services, including four helicopters and 15 ambulances, raced to the scene
• Police say the driver was arrested at the scene

Nine people have been injured after a car hit a crowd of Newcastle Knights supporters this morning.

The crowd had gathered as part of a pre-grand final farewell to the team at Wallsend.

Police have arrested the driver.

Stay with us as we bring you the latest updates.