The crash, between a Vauxhall and a Peugeot, happened at around 2.10pm today.
NARS paramedic Simon Nunn was dispatched from his home and was the first on the scene, where he helped care for five patients.
One had suffered 'significant injuries' and Mr Nunn requested critical care support and provided pain relief pending the arrival of the air ambulance.
The injured person was sedated before being extricated from the vehicle by Norfolk Fire and Rescue crews from Swaffham and Thetford, and was then airlifted to the Norfolk and Norwich University Hospital in a serious but stable condition.
Three ambulances and an ambulance officer were sent to the scene.
Three other patients were treated for minor injuries and were taken to hospital by land ambulance.
Police are still on the scene and the road is closed which is causing delays.
Diversions have been put in place and police are asking drivers to avoid the area.
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