An ambulance was one of four vehicles involved in a crash on the A6 this morning (Tuesday).
Police were called to the busy route between Burton Latimer and Finedon at about 7.30am.
A force spokesman said: “We were called after a crash between two cars, a van and an ambulance.”
This afternoon East Midlands Ambulance Service (EMAS) said the collison took place when the ambulance was responding to a 999 call.
Mick Jones, service delivery manager for Northamptonshire, said: “An ambulance responding to a 999 call was involved in a road traffic collision at 7.28am on March 5 on the A6 near Burton Latimer, Kettering.
“A paramedic in an ambulance car and two crewed ambulances were sent to the scene.
“Two patients from other vehicles involved in the collision were taken to Kettering General Hospital.
“The incident will be investigated by the police and it is therefore inappropriate to make any further comment at this time.”
The road has since re-opened.