How rumours spread on twitter

Earlier today a rumour that there was a gunman at large in Oxford Street spread around London.  This seems to be how it happened.

A fashion assistant for the online store ASOS was trying to recruit bystanders for a photo shoot that was going to happen, and she at tweeted at 11.17am:

Unfortunately some people who saw the tweet misunderstood, and the message started to get garbled, including:

"Shooting in progress in Oxford Circus? What?" - 11.20 am

"Gun alert on oxford circus right now? is it true?" - 11.25am

"Gunman loose in Oxford Circus?" - 11.26am

"is there a shooting in Oxford Circus right now???? this is what i'm hearing" - 11.26

"shooting in oxford circus - talk of the office. True or Hoax?" - 11.27am

"@BBCBreaking @SkyNews is there a shooting at oxford circus right now, that what i'm hearing. or is it a hoax email i've got??" - 11.27am

"Apparently theres a shooting at Oxford Circus, gunmen on the move. We've been told to stay in. Guess I'm not gonna have McDonalds lunch then" - 11.28am

"Shooting in progress in Oxford Circus, stay safe people." - 11.28am

& so on...

(Full grabs and list of tweets here)

'Oxford Circus' became a trending topic, news channels and the police investigated...  It's easy to see how these rumours start, but luckily twitter was also able to spread the denial very quickly too.