A motorcyclist has sustained life-threatening injuries in a crash.

Police are investigating a serious collision which happened on the A414 dual carriageway at around 1.15pm (Sunday September 20).

Hertfordshire Constabulary says the crash happened on the westbound carriageway between the Park Street roundabout, near St Albans, and M1, near Hemel Hempstead.

It involved a Fiat 500 and a motorbike and the motorcyclist has suffered life-threatening injuries.

Road closures have been in place on the A414 and at junction 8 for the M1.

Highways England tweeted shortly before 5pm that the eastbound carriageway towards St Albans will reopen shortly but the road will remain closed towards Hemel Hempstead.

A witness appeal has been launched by police.

Sergeant Sam Cordingley from the Bedfordshire, Cambridgeshire and Hertfordshire road policing unit, said: "I am appealing for anyone who witnessed the collision, or events leading up to it, to please get in touch.

"I am particularly keen to hear from anyone who may have captured dash cam footage which could assist our enquiries, as we work to establish the circumstances surrounding the collision. If you can help, please get in touch."

Anyone with information can visit herts.police.uk/report or call101 quoting ISR 369 of 20 September.