Officers are appealing for witnesses, information and dash cam footage following a collision in St Albans.
Police were called by the ambulance service at around 7.13am this morning (Monday, June 13) to report a collision in Verulam Road.
Two vehicles were involved, a van and a motorcycle.
The motorcyclist was taken to hospital with serious injuries.
The driver of the van was arrested on suspicion of driving whilst under the influence of drugs.
Sergeant Timothy Davies, from the Bedfordshire, Cambridgeshire and Hertfordshire Road Policing Unit, said: “This was a serious collision on a busy road, which took place right before peak rush hour times. We believe that several people would have seen this collision taking place or witnessed the events leading up to it or immediately after.
“If you did, and have not yet been in contact with police, please get in touch as soon as possible. Any information, even something that may seem relatively minor or insignificant, could be key to progressing our investigation.
“I would also like to ask anyone who was driving in the vicinity of Verulam Road around the time specified who has a dash cam fitted to their vehicle, to review the footage and send us anything you think may be of note.”
You can email Sergeant Davies at email@example.com, report information online at herts.police.uk/report, speak to an operator in the Force Communications Room via the online web chat at herts.police.uk/contact or call the non-emergency number 101, quoting ISR 106 of 13 June.