Harvey Evans, 15, and Kyrees Sullivan, 16, were killed on May 22 in the Ely suburb of Cardiff (Picture: PA/Wales News Service)

The families of two boys killed in a crash in Cardiff have protested about how they were treated by police.

Tensions between people and police at the spot where Kyrees Sullivan and Harvey Evans died led to a riot lasting several hours, during which dozens of officers were injured, property was damaged and cars were set alight.

This came as CCTV showed a police van travelling close behind their e-bike in the run up to the incident in the Ely suburb on May 22.

South Wales Police is now being investigated over its ‘response and management’ of the scene on the night.

The Independent Office for Police Conduct (IOPC) is also probing the treatment of the families of the teenagers, and the force’s communication with them.

A statement from the watchdog said: ‘Our original investigation into South Wales Police and the interactions with the teenagers before their deaths is at an advanced stage.Evidence gathering from our enquiries in Ely has been completed.

‘We have taken a large number of statements from local residents as the result of our house-to-house enquiries.

‘We have reviewed hundreds of videos as well as body-worn video from officers who were at the scene.We have also taken further statements from officers and staff.’

The IOPC confirmed it has identified further lines of enquiry which we arebeing pursuing as a ‘priority’.

The watchdog previously said the driver of the police van, an officer with South Wales Police, was told they were being criminally investigated for dangerous driving after previously being served with a gross misconduct notice.

Another officer, a passenger in the police van, was also previously served with a gross misconduct notice.