David Cameron has praised the "courage" and "sacrifice" of the Armed Forces.
His tweet comes as Armed Forces Day is being celebrated across Britain.
Today we pay tribute to the courage, determination and sacrifice of our Armed Forces. Their bravery keeps all of us safe. #ArmedForcesDay
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The Westminster terror attack dominates the front pages of Thursday's newspapers.
A timeline of exactly what happened.
Tobias Ellwood, MP for Bournemouth East and Foreign Office Minister, attempted to save the life of the stabbed officer in Westminster.