Emergency services are at the scene of a three-vehicle crash on the A45 near Wellingborough.
Police were called to the westbound stretch of the dual carriageway, near the Wilby Way roundabout, after the crash at about 4.20pm this afternoon (Thursday).
A police spokesman said two of the vehicles are believed to be a lorry and a 4x4.
The air ambulance is landing nearby. Police were unable to confirm the severity of injuries at this stage.
A force spokesman said the road is expected to be closed for some time.