How a rumour causes panic

Police and pompiers after false alarm at Juan les Pins

The use of instant messages on social media (Twitter, Facebook et al) to spread so-called information had an unfortunate turn on Sunday evening at Juan les Pins on the Cote d'Azure. Late night drinkers heard an explosion, so took refuge in the bars. Someone tweeted "attentat a Juan les Pins". This was re-tweeted, with many asking the 24 hour news networks for confirmation or advising locals to go home.
20 minutes later France Bleu radio issued a denial of any attack, the gendarmes explaining that a car backfiring was the cause of the noise. But in the panic over 70 people were injured.
As often with these things there was an actual event (the backfire), but internauts were too quick to describe the event as an attack. The rumour was quickly spread as fact and the groups interested in spreading panic soon jump on board.
The national gendarmerie has a message on its Twitter page asking people not to propagate unsubstantiated information.
Hoaxes and rumours

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