More than 200 police officers and police support staff in London took part in a major exercise Sunday on the River Thames to test their response to a terror threat on the British capital.
London's Metropolitan Police along with emergency services, carried out the first joint major live-play exercise on the river while thousands of people look on.
A spokesman at Scotland Yard more than 200 Met police officers and staff took part in the exercise, code named "Exercise Anchor".
The scenario involved a group of terrorists hijacking a passenger pleasure boat on the Thames and taking a number of hostages, to travel up the Thames to Central London to carry out a terrorist attack.
It was designed to test the response and command and control protocols of emergency services, working with maritime partners, in dealing with this kind of situation in a marine environment.
The exercise tested the Met's processes right from an emergency call handler receiving the initial call through to getting victims and suspects safely off the vessel once secure. This included intelligence officers identifying and locating the threat, 'command and control' structures put in place and officers deployed to deal with and confront the threat.
It also tested how different agencies on the river work together in this kind of scenario.
Counter Terrorism Specialist Firearms Officers (CTSFOs) were deployed during the exercise alongside the Met's Marine Policing Unit and intercepted the "suspect" vessel, boarding and securing it.
The coordination of search and rescue teams was then put to the test with a "dummy" body falling into the river, challenging those responding in how to rescue the person in the midst of an ongoing terrorist incident. Police officers used marine-trained search dogs on board the vessel.
The Met spokesman said an official review of London's preparedness to respond to a terrorist attack last October recommended that security measures on the river be strengthened.
The current terrorism threat level in Britain remains at severe meaning that an attack is "highly likely" with members of the public urged to remain vigilant.