They always say that.
At this point, nobody really KNOWS, whether it was an accident or deliberate.
But the fact that it happened shortly after the Scotland Yard issued a nationwide alert about Al Qaeda attacks, makes it quite reasonable to include the possibility of terrorism as one of the possible causes.
That's true. However various things are making me more sure that an aircraft wasn't involved.
*incident was 2 hours ago, normally if a plane goes down there is confirmation from air traffic control by this time.
*Air traffic is still going in and out of Luton - if this was a terrorist attack with a plane, would have grounded all the others.
*Sky News have interviewed various witnesses who were quite close to the actual explosion - none of them have mentioned any possibility of a plane. The rumours have come from people miles away, some of whom only report 'a noise that sounded like a plane going overhead' - could well be that this was the beginning of the explosion.
And Police now specifically saying that reports of a plane going down are 'untrue'.