The A45 is closed between Stanwick Lakes and Raunds after a serious crash this morning (Friday).
Police, fire and ambulance were called after the incident on the eastbound carriageway at about 7.20am which involved a transit van, an Audi and a VW Golf.
A police spokesman said two people have been taken to University Hospital Coventry by air ambulance with serious injuries.
Another has been taken to Kettering General Hospital.
Officers are still at the scene and traffic is being diverted through Stanwick. It is not known when the A45 will re-open.
Witnesses should call the Drivewatch Hotline on 0800 174675.