I’m missed this story breaking on Feb 1, but it seems a guerilla marketing exercise for the excellent Aqua Teen Hunger Force has caused multiple security alerts in Boston. It seems a third-party marketing firm working for the Cartoon Network, put up electronic light displays depicting a Mooninite character greeting bean-town citizens and visitors with an upturned middle digit. Somehow, the light boards were misinterpreted as suspicious devices.

Boston then swung into a full security alert. Local, state and federal law enforcement agencies shut bridges and sections of the Charles River – CNN then reported that US Northern Command was monitoring the situation from its Colorado Springs headquarters.

Two men involved in planning and executing the stunt have been arrested, the Massachusetts attorney general Martha Coakley has confirmed. The charges they face include a felony - placing a hoax device that caused panic - and a separate count of disorderly conduct.

It remains a mystery as to why a full security alert was called on Wednesday over advertising devices that had been present in Boston - and other major US cities including Atlanta, Philadelphia, New York and Los Angeles - for the past two weeks, although Coakley attributed it to the devices having a “very sinister appearance” and “wires”.

Turner Broadcasting spent most of Wednesday evening apologising for the chaos both in the form of a written statement and by on-air captions during Cartoon Network programming.