A motorcyclist in his 20s has died after coming off his bike on the A414 in Hemel Hempstead.
A fast response car, ambulance and emergency helicopter rushed to the Breakspear Way stretch of the dual carriageway after a 999 call just before 3.45pm today.
But the first paramedics there said he was dead by the time of their arrival.
Police closed the road in both directions – but the westbound stretch of the A414 has since been reopened, the Highways Agency reported.
Spokesman Baz Abdulla said: “There is a lot of congestion in the area as a result of the incident, which is ongoing.”
UPDATE:
Police have said that the motorbike, which was travelling towards the M1, was the only vehicle involved in the collision.
Spokesman Sarah Spence said: “The rider sadly died at the scene. The road has been closed for investigations to take place at the scene.”
Anyone who witnessed the incident – or who has any information on what happened – is asked to phone police on non-emergency number 101.