A group of youths were caught on video performing stunts on their motorbikes while crossing a bridge into Kent.
A man on a motorbike and another on a quadbike were wheeling on the Dartford Crossing and driving dangerously at 2.50pm on Saturday.
It has not been reported to the police yet.
From the video the vehicles look to be lacking number plates.
Police spokesman, Sally Smith, said: “We are aware of Tweet which shows a video clip of apparent dangerous riding.
“When this is reported to police we will investigate.
Motorcylists were caught preforming dangerous stunts on the Dartford Crossing
“Witnesses are asked to contact Kent Police on 101.”