A motorcyclist was airlifted to hospital with a serious head injury after a crash.
The man, in his 30s, was involved in a crash with an Audi while he was riding his Honda CBR 600 in Ridge Hill, near London Colney, just after 5.30pm on Friday.
The driver of the Audi, a woman, suffered minor injuries.
Police officers investigating the incident are now appealing for information and witnesses.
Bedfordshire, Cambridgeshire and Hertfordshire Road Policing Unit, sergeant Will Hood said: “We are working hard to piece together what happened in the lead up to the collision.
"We have closed the road to conduct a thorough investigation at the scene.
"Many people would have been making their way home from work at the time so there would have been a fair volume of traffic.
“We are asking members of the public who witnessed what happened, or saw the vehicles involved prior to the collision.
"Please call us on 101 or report online at http://socsi.in/Vg1XO, quoting ISR 619 of May 11."
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