According to German media reports, it was an Easyjet flight from Llubjana en route to Stansted. A passenger reportedly overheard two fellow passengers talk about a "bomb" or "explosives" and informed cabin crew which passed this on to the flight deck. The captain then decided to divert to Cologne, where the aircraft was evacuated via slides. A backpack that had been found but could not be accounted for was blown up by police,
Bild reports citing "a witness". No information yet on what the backpack contained. According to police sources, three men with a "direct connection" to that backpack have been arrested. The plane is currently being searched for explosives.
(Take this with a grain of salt, some of it has been reported by tabloids. What we can assume as fact from photos is that the plane is in Cologne and has been evacuated via slides).
Express story with pics