Motorists were being told to find an alternative route out of Huntingdon after a collision in Hartford Road.
Police said vehicles coming into Huntingdon were being diverted via Desborough Road and that vehicles coming out of Huntingdon “need to find alternative route”.
A Cambridgeshire police spokesman said: “We were called at 6.42am today (Monday, July 8) with reports of a collision in Hartford Road, Huntingdon, involving a car and a motorbike.
“Officers and paramedics attended the scene of the collision, which initially blocked the road in both directions.
“The motorcyclist has been taken to hospital with serious, but not life-threatening injuries. The road is now clear.”