Major Incidents | Operations | Slideshow | Training

London Terror Exercise

01 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, a medic treats a casualty, outside the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

02 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, a casualty is helped to leave the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

03 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, a casualty is helped by an armed police officer, outside the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

04 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, an armed police officer walks with a casualty away from the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

05 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, a woman playing the role of a casualty shows distress outside the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

06 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, a casualty is dragged away by rescue officers from the London Fire Brigade, outside the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

07 / 08

Britain Terror Exercise

During a training exercise for London's emergency services, a casualty is carried away by police officers, outside the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)

08 / 08

Britain Terror Exercise

People take part in a training exercise for London's emergency services outside the disused Aldwych underground train station in London, Tuesday, June 30, 2015. Hundreds of British police are taking part in a major counter-terror exercise in London, testing the abilities of emergency services to respond to a Tunisia-style attack of extremists with firearms. The exercise dubbed Operation Strong Tower has been planned for six months and is not connected to the recent attack at a north African beach resort. (AP Photo/Matt Dunham)