A police officer who died after his car crashed as he responded to an emergency call was named by North Yorkshire police as Pc Andrew Bramma, 32.
The officer was killed when his patrol vehicle collided with a tree in the village of West Tanfield, near Ripon, at 7pm on Saturday.
The married father-of-two was the only person in the vehicle when it crashed and he was pronounced dead at the scene.
Temporary Chief Constable Tim Madgwick said: "This is terrible and tragic news and the thoughts of everyone at North Yorkshire police are with the officer's family at this sad and very difficult time.
"Everyone is shocked and saddened by the news of his death and I speak for every member of the force in extending our heartfelt sympathies to his family, friends and colleagues."
The road was closed for several hours last night as collision investigators examined the scene.
The Health and Safety Executive has also been informed and an investigation will be carried out into the cause of the collision, police said.
Anyone who was in the area at the time and saw the vehicle or witnessed the collision is asked to contact North Yorkshire police on 101.