Been closed in both directions at Dartford Crossing due to a man 'acting suspiciously'. God knows whats going on 
Sky News:

Sky News:
A spokesman for Kent Police said a "suspicious item" had been found on the bridge, while a man who was "behaving unusually" has been arrested.
The crossing is expected to be closed for some time, with drivers urged to find alternative routes.

And yes, they're turning the vehicles around.