Twitterer Mike Mompi's got a good image of what's going on. From his twitter page:
Update 16:31hrs GMT, Statement from London City Airport's website:
“London City Airport can confirm that a technical issue occurred onboard Swiss flight LX437 due to depart to Geneva at around 15.00 on Thursday 27 March 2014. 74 passengers and four crew were evacuated immediately and three people were treated at the scene for minor injuries by the London Ambulance Service.
The runway was closed temporarily and re-opened at 16.15.”
Update: 16:20 hrs GMT, runway is now open again. Very efficient work from London City Airport!
Update 15:54hrs GMT All flights into and out of London City Airport are currently suspended.