A man has been arrested after a female driver died in a collision involving three vehicles.
The incident happened on the A602 near Hitchin in Hertfordshire at about 18:45 GMT on Sunday.
Police said the crash involved a black BMW 3161, a grey Toyota Corolla and a silver Hyundai IX35.
The driver of the Toyota, a woman in her 50s, died at the scene and the driver of the BMW was arrested on suspicion of dangerous driving.
The 24-year-old man, from London, was also arrested on suspicion of failing to provide a sample.
Det Con Felicity Moody, from the Bedfordshire, Cambridgeshire and Hertfordshire Road Policing Unit, said: "Our thoughts are with the lady's loved ones at this very difficult time.
"We are working to establish how the collision occurred and we want to hear from anyone who can help."
Police appealed for dashcam footage and witnesses to the crash or the events leading up to it.