Emergency services in London staged a major drill on Wednesday to test their response to a terror attack.
The simulation involved three assailants shooting their way into an underground station. Authorities said the drill had been planned long before last week's shootings on a beach in Tunisia.
Fourteen agencies were taking part in the drill, according to officials, including medical, fire and police services, as well as soldiers and intelligence officials.
The exercise goes on for two days, and was being staged at the disused Aldwych underground station in central London.