One lane is blocked on the northbound carriageway between Southoe and Buckden following the collision, which occurred at about 7.30am. Motorists are being advised to allow extra time for their journeys. Police and other emergency services are at the scene. A spokesman for Cambridgeshire police said: We were called at 7.41am to the A1 northbound near Buckden to reports of a road traffic collision.The collision involved three vehicles. Officers attended the incident, together with paramedics. Two people are believed to have suffered minor injuries. One lane is closed while the incident is dealt with. Motorists are urged to take alternative routes.