Four people have been injured, one seriously, following an incident between Stevenage and Watton-at-Stone.
Two vehicles, a black Audi Q2 and a grey Seat Leon, were involved in a head on collision on the A602 at around 1.25pm on Saturday.
The driver of the Seat suffered serious injuries. The driver and two passengers in the Audi were also injured.
Herts police would like to speak with anyone who saw what happened, or saw events leading up to the collision.
Information can be reported online, via online web chat or by calling 101, quoting ISR 349 of December 4.
Alternatively, reporters can stay anonymous by contacting Crimestoppers on 0800 555 111 or via their untraceable online form.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here