Police were called at about 9.15am to reports that two cars had collided on A1, at its junction with the A14, at Brampton Hut. One of the vehicles, a Land Rover Discovery, overturned after reportedly colliding with a police firearms vehicle. There were no reports of any serious injuries. Highways England closed the northbound carriageway while emergency services work to clear the scene. A spokesman for Cambridgeshire police said investigations into the collision had been completed and the road re-opened to traffic at about 1pm. Motorists are being advised to expect delays while traffic flows return to normal.