A critical incident investigation has been launched following a truck crash at Singleton, NSW Police say.
Just before 7.30am tomorrow, police responded to reports of a semi-trailer stolen from a service station at Murrurundi in the Hunter Valley.
The truck was allegedly sighted driving erratically south along the New England Highway, through Muswellbrook and towards Singleton.
A pursuit was not initiated.
As the truck approached Singleton, officers deployed road spikes in order to stop the vehicle.
The truck continued into George Street, Singleton, where it caught fire after crashing into several vehicles and buildings, injuring a number of people.
A man in a vehicle was taken to John Hunter Hospital in a critical condition.
The driver of the alleged stolen truck was arrested at the scene and is currently assisting police with inquiries.
A critical incident team from Port Stephens Local Area Command will now investigate all circumstances surrounding the incident including the deployment of road spikes.
That investigation will be subject to independent review.
No further details are available at this time; however, police are appealing for witnesses to come forward.
Anyone who can assist police should contact Crime Stoppers.