Two people are critically injured and another two hospitalised after an allegedly stolen truck crashed into multiple vehicles and caught alight in Singleton, NSW.

.

Police said that man was in one of the vehicles and was in a critical condition.

The licensee of the Horse and Jockey Hotel described the aftermath as “absolute carnage”.

The fire also spread to the ground below after burning debris from the truck rained down, RFS Inspector Ben Shepherd told AAP.

“He was going at least 100km/h. some cars have been taken out by the truck. When he crashed, he got out of his truck, and tried to get into another truck”.

NSW Police told Daily Mail Australia the accident occurred on George Street at Singleton shortly before 7.30am Wednesday morning.

Emergency services were called to the Wingecarribee Bridge near Berrima around 9am on Wednesday following reports the prime mover had gone up in flames, police say.

All four are being treated at John Hunter hospital in Newcastle.

A second rescue helicopter was summoned from Sydney.

Huge blankets of black smoke can be seen and one witness reportedly said there was a “huge fireball” with cars “all over the road”.

The truck was seen driving erratically along the New England Highway through Muswellbrook towards Singleton.