DARTFORD Tunnel came to a standstill as dozens of firefighters, paramedics and police officers took part in a disaster scenario.

The two tunnels were closed as emergency crews battled to contend with a lorry blaze, jack-knifed milk tanker, two fatalities and dozens of walking wounded.

Traffic was diverted via the A2 and Blackwall Tunnel while the emergency exercise, Operation Orpheus, took place between 1am and 6am on Sunday.

The massive operation, involving 700 participants and observers, was declared a success.

John Aspinall, the South East director of the Highways Agency, said: "It has been a really huge effort and there has been some really good organisation.

"The big message is that this is all about a multi-agency approach. It has been a fantastic event seeing how people work together.

"The speed of people getting to the tunnel and beginning to work together has been amazing."

The disaster scenario unfolded in the west tunnel, while the east tunnel was closed to allow access to emergency crews.

In the exercise, which was written by Kent Fire and Rescue Service, a lorry carrying tyres hit the tunnel wall and burst into flames, creating clouds of smoke in the tunnel.

In a separate incident, a milk tanker jack-knifed across the tunnel, creating a pile-up of vehicles behind it, including a double decker bus.

Later in the scenario, the lights went out in the section of the tunnel where firefighters were battling the blaze, making their work even tougher.

The parts of the "victims" were played by the Royal Gurkha Rifles and soldiers from the 2 Infantry Brigade – both based at Shorncliffe Barracks in Folkestone – and Essex Police cadets and actors from the Casualties Union.

Kent Police’s Assistant Chief Constable, Adrian Leppard, observed the operation from a marquee set up at the offices of Le Crossing, the company which operates the tunnel and bridge.

He said: "I think we responded very quickly and very effectively. We heard how the command and control structures were being brought together.

"One of our roles is to coordinate the other emergency services, and I think we did that."