Emergency services raced to the A6 at Burton Latimer this afternoon (Sunday) after a serious crash.
Two cars were involved in the crash just after 2pm.
Police closed the bypass between Higham Road and the Seasons roundabout.
Fire crews from Wellingborough and Kettering attended the scene and the air ambulance landed nearby.
Two people were released from the vehicles by the fire crews.
The severity of their injuries is not yet known at this stage.
The road is expected to remain closed for at least another hour.
EDITOR'S NOTE: An earlier version of this story stated four people were freed from the cars involved, two from each car. The fire service has since confirmed one person was freed from each car.