After a traumatic night which saw rioters torch cars, volley fireworks at police, and indulge in nine hours of mayhem, residents of the close-knit Ely, in Cardiff, are left to deal with the reality of what a rumour can do in the social media age.

It started on Monday evening. A tragedy which would usually define such a night was only the beginning of the destruction which followed. On Ely’s Snowden Road, two teenage boys said to be riding an off-road bike or scooter, were killed in a crash. Such a harrowing event was the catalyst for what reporters on the ground described as a ‘war zone.’

As news of the crash filtered across social media, a reported 150 people later gathered at the scene of the crash. Tensions soon boiled over with police and gangs staging pitched battles as cars went up in flames and terrified residents watched from their windows in horror.

Until 3 a.m. rioters torched cars, set ablaze wheelie bins, and smashed up whatever got in their way

Scenes circulating on social media show some members of the crowd blasting fireworks at the phalanx of specialist riot police officers lined up before them. Videos show strings of masked rioters marching toward police lines as fireworks rip through the air and bounce off police riot shields. At least 12 officers were injured.

Until 3 a.m. rioters torched cars, set ablaze wheelie bins, and smashed up whatever got in their way. A resident named Jane Palmer, speaking to the BBC, said the mob lit up her car. She and her family watched from their window as the vehicle went up in flames.

‘I’m disabled, so now I’m trapped without my car,’ she told the BBC. ‘Why are they doing this? It’s just silly now.’

Residents of Ely woke up to a warzone. Torched cars litter roads strewn with broken glass and the debris of the rioters’ indulgence.

The power of social media cannot be understated. A rumour, suggesting there was a police chase in the lead-up to the fatal accident, spread quickly. Fizzing around social media, that report led to a night of pure destruction and wanton violence, the kind of which will sear itself into the history of the deprived, close-knit community of Ely.

Police deny the chase ever happened, insisting officers learned of the tragedy only after being called to the scene just after 6 p.m. on Monday evening. Speaking to BBC Wales, Police and Crime Commissioner Alun Michael said what began as a fatal traffic accident tipped into violent disorder after rumours laid the blame at the hands of the police.

‘It would appear that there were rumours – and those rumours became rife – of a police chase, which wasn’t the case. I think it illustrates the speed with which rumours can run around with the activity that goes on social media nowadays, and that events can get out of hand,’ he said.

But a video published by the BBC appeared to show that police were tailing two people on an electric bike shortly before the fatal crash. The video, was captured on Frank Road in Ely, a short distance from the site of the accident.

Whatever did unfold in Cardiff last night, the power of social media to amplify events is clear. Much of the violence was live streamed across YouTube, Instagram, and Facebook, showing hordes of rioters launching rocks at police. In an orgy of false information, rioters reportedly attacked an innocent member of the public after falsely believing them to be an undercover police officer.

In a statement issued this morning, South Wales Police said officers had arrived after the fatal collision: ‘Shortly after 6pm yesterday, we received a report of a serious road traffic collision on Snowden Road, which resulted in the deaths of two teenage boys.

‘Police responded to this collision which had already occurred when officers arrived, and they remained on-scene to manage a large-scale disorder until the early hours of this morning. Specially trained public order offences were also deployed, including officers from neighbouring police forces.

‘Several vehicles were set alight, property was damaged, and police officers were injured during the incident.’

The chaos in Ely demonstrates the power of social media. With just a smartphone, and a rumour, anyone so inclined can lather a community into nine hours of destruction.

Today, the residents of Ely, a community which formed my first beat as a young reporter, wade through broken glass, with the indelible stench of burnt rubber in the air.