A 16-year-old girl who died after being hit by a police car had been due to sit her GCSE English exam today.
Hayley Adamson died in hospital after she was hit crossing a road at 11.20pm last night.
Police in Newcastle have appealed for calm after violence flared and an officer fired his Taser gun immediately following the accident.
An Independent Police Complaints Commission investigation has begun into the crash.
Hayley, a pupil at Sacred Heart High School, was with friends when she was hit by the car on Denton Road, Newcastle.
Tributes were laid outside the home she shared with her mother on Cedar Road, Fenham.
An IPCC spokesman said a Northumbria Police driver had been responding to the activation of his vehicle's automatic number plate recognition system.
Gary Garland IPCC Commissioner for the North East said: "It is unclear at this stage whether the car's emergency warning equipment was activated.
"Ms Adamson was crossing the road with friends when the collision occurred.
"Following the collision there was an incident involving a member of the public at the scene which culminated in a police officer discharging a Taser stun gun.
"A 23-year-old man has been arrested.
"The IPCC will also examine the circumstances involving this incident.
"This is a terrible tragedy and my sympathies go out to Ms Adamson's family and friends and all those involved in the incident.
"The IPCC's investigators have been at the scene since early this morning following the referral of the case by Northumbria Police.
"We will undertake a thorough independent investigation into all the circumstances of the incident."
Northumbria Police said the driver was alone in a marked Volvo T5 patrol car at the time of the accident.
Chief Superintendent Paul Wier said the officer had gone off duty and was being investigated by the IPCC. He appealed for calm.
He said: "Emotions are running high that is understandable.
"We have a lot of police out on the streets at the moment and would like to reassure the community that their streets are safe.
"There was a number of arrests made last night for violence and disorder immediately following the incident.
"People were distressed and some people were throwing bricks.
"The best thing everybody can do now is to keep calm and allow the IPCC to do their jobs and investigate this incident.
"The officer was alone in his car, he has gone off duty now and he will be investigated in due course."
He said no police equipment had been damaged during the violence and said the Crown Prosecution Service was considering whether to charge those arrested.
He said no one was arrested in connection with the death itself.
Roads around the collision scene were closed as investigators gathered evidence and traffic diversions were in place.
Hayley's head teacher at Sacred Heart Roman Catholic High School, Patricia Wager, said: "Hayley was a happy, popular and fun-loving student.
"There is a sense of shock at the school today and we are supporting her classmates and friends.
"Our thoughts and prayers are with her family at this difficult time."
One of many tributes written to Hayley on the Gone Too Soon website read: "Hayley Adamson was only 16 when she had her life taken away on 19th May 2008.
"She was from Fenham but was always in the area of Scotswood where her sister, Sarah, lived and all her friends. Hayley was such a loving and caring girl she would do anything for anyone as anyone who knew her will know. She was always laughing and carrying on.
"She was only 16, she was looking forward to leaving school this week.
"That's all, she talked about these last few days. She still had the whole of her life ahead of her and we will miss her so much."
The tribute was posted beneath a picture of two teenage girls wearing tracksuits, smiling and hugging.
Assistant Chief Constable Sue Sim said: "We deeply regret the loss of a young life and our thoughts are with her family and friends at this time.
"We continue to offer every possible assistance to the independent investigators so they can establish the full circumstances leading up to Hayley's death."
The IPCC said the police driver had been responding to the activation of his vehicle's automatic number plates recognition system.
Some police cars are fitted with cameras which read number plates from passing vehicles and that information is fed into a database which alerts officers to cars which might be stolen or be otherwise of interest to the police.
Hayley's sister, Sarah, from Scotswood, Newcastle, was too upset to speak yesterday.Reuse content