We hope it's nothing serious obviously, but according to Twitter something happened just past 8am EST today at London's Heathrow terminal five. Tweets are claiming armed police (picture here) are evacuating the whole terminal. [Twitter]

UPDATE: Twitter user @MartinBrunt says "Armed police in stand-off with man threatening to blow himself up at Terminal 5 Heathrow. Terminal evacuated."

UPDATE 2: Heathrow terminal five has been reopened.