A man arrested in connection with a bomb hoax which led to the Dartford Crossing being closed in both directions and severe delays on the M25 has been detained under the Mental Health Act.
The 27-year-old was in police custody since being arrested on Friday and has now been taken to a secure unit under the care of the Health Authority, a spokesman for Kent Police said.
The man, from Bournemouth in Dorset, is alleged to have made threats of a suspicious device on board the coach he had been travelling on before making further threats about an explosive device on another coach.
The incident led to motorists being caught in nine-mile long tailbacks after both the QE2 Bridge and Dartford Tunnels were closed for almost seven hours during rush-hour traffic on Friday night, while traffic was also stopped from using the A20 at Dover.
Police said they recovered a cylindrical device with wires heavily sealed inside a bag from the first coach.
It was found after the force was called at 4.03pm to a report of a male pedestrian behaving unusually. He had alighted from a coach which was Dover-bound and run to a rough area nearby, police said.
Security personnel at a nearby distribution depot detained the man and officers arrested him at 4.15pm before he was taken to a police station where he made threats as to a suspicious device on board the coach.
The vehicle, which had just gone through the toll booths, was evacuated along with the immediate surrounding area, which was extremely busy at the time.
Bomb disposal experts attended the scene and a robotic device was deployed to examine the device more closely.
Police said the detained man made further threats that there was an explosive device on another coach and officers then stopped a coach on the A20 at Dover at 6pm. It was evacuated and the road was closed before being reopened at around 10.45pm after no threat was found.
The Dartford Crossing was reopened at around 11.45pm, police said.
Assistant Chief Constable Rob Price said today: "We were dealing with a very challenging situation, with two scenes in extremely busy areas. Our main priority was to ensure the safety of the public, our officers and our partners at the scene.
"We had received threats of a very serious nature that required regional and national co-ordination and declared this as a critical incident. Obviously a lot of people were caught up in long delays but this could not be avoided as we had to ensure public safety and as soon as clearance was obtained the road was immediately opened.
"We would like to thank the public for their patience last night, and also thank our partners, the Explosive Ordnance Disposal Team, South East Coast Ambulance Service, the Highways Agency, Kent Fire and Rescue Service, Kent County Council and others who all worked to ensure the safety of everyone involved."
Motorists crossing the Dartford Tunnel reported seeing a man walking near the toll booths shouting.
Van driver Paul Auty, 39, told the Daily Mail: "This man was wandering around between the lines of traffic waiting to go through the toll booths, and he was waving his arms around and shouting."
Photographs posted on social networking site Twitter showed long queues of stationary traffic with many commuters standing outside their vehicles.
Laura Wilcock posted on Twitter: "Finally home and in my bed after a very long 9 hours stuck on the dartford bridge. Scary stuff. I hope everyone gets home safely xx"