A decommissioned ambulance crashed into a level crossing while fleeing the scene of a fatal crash involving two other vehicles.
Officers pursued the former emergency vehicle - which had its blue lights on - for about 30 miles.
It eventually hit the barrier near Kildwick, North Yorkshire, after driving from the first crash scene on the A65 between Clapham and Ingleton.
A 41-year-old man from Halifax fled the crossing but was later arrested.
It was thought to have been in convoy with a flatbed truck, converted into a campervan, which collided head-on with a car at about 16:15 GMT on Friday
A passenger in the car, a 28-year-old man from Wigan, died at the scene.
The campervan driver, also a 28-year-old man from Halifax, was arrested on suspicion of causing death by dangerous driving and driving while unfit through drink or drugs.
Officers are appealing for anyone with dashcam footage or who saw the vehicles' movements to get in touch.
A spokesman said: "The converted campervan was quite distinctive due to the crudeness of its conversion which is described as a flatbed truck converted into a camper.
"The decommissioned ambulance used its blue lights during its journey towards Skipton."