A member of the public is believed to have broken their ankle while stopping to help when a car caught fire along the A422.
The road has now been closed in both directions between the A509 junction in Chicheley and the Main Road junction in Astwood.
Firefighters from Newport Pagnell were called after reports of a car fire at 10.40am this morning and alerted Thames Valley Police who arrived at 11am to manage traffic.
The Highways Agency were informed of the incident because of damage caused to the road surface.
The Citizen is waiting on confirmation of the victim’s condition from South Central Ambulance Service, but the man is believed to have fallen and sustained a broken ankle.