Hayley Adamson died in hospital after she was hit crossing Denton Road in Newcastle at 11.20pm on Monday, the day before she was due to sit her GCSE English exam.

Angry witnesses confronted police, some throwing bricks, and officers appealed for calm while the Independent Police Complaints Commission investigates the tragedy.

Chris Broatch, 23, said he saw the crash from his home on Dorset Road, close to the scene of the collision. "Hayley followed her mate across the road and the police car came and hit her," he said. "She was all dressed in white so I don't know how he didn't see her. It was because he was going far too fast. He had the headlights on but no blue lights or a siren."

He said the police car was travelling at "about 100mph - that fast" when it hit Hayley.

Mr Broatch said about 50 people congregated around the scene of the crash and were "giving the police abuse".

"The driver got out and said 'It's my fault' because he was going to get lynched. Not one of the police helped her - not one of them checked her pulse. They just held people back and said keep calm. Everyone was shouting at the police to lock up the policeman who knocked Hayley down."

An IPCC spokesman said that a Northumbria Police driver had been responding to the activation of his vehicle's automatic number plate recognition system.

Some police cars are fitted with cameras which read number plates of 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.

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."