The flag at Hertfordshire Police headquarters is flying at half mast in honour of a police officer who was killed in a terrorist attack in London.
PC Keith Palmer of the Metropolitan Police was stabbed to death by a terrorist while he was working at the Palace of Westminster yesterday.
READ MORE: London attack: Herts Police response is 'strong visible presence'
The attacker, who was shot dead, also drove along the pavement of Westminster Bridge, killing three people and injuring a further 40.
A 43-year-old Spanish teacher, Aysha Frade, was among those who died in the attack. It is believed she was walking from school over the bridge when she was hit by the car.
READ MORE: Police shoot ‘knife wielding man’ at parliament after car mows down five people on Westminster Bridge then crashes into railings
Seven people have been arrested in connection with the incident, which is believed to be linked to Islamic terrorism.
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