At around 2.40pm the attacker drove across Westminster Bridge, mowing down pedestrians, before stabbing a policeman outside Parliament. He was shot by armed officers.
Police confirmed five people, including the attacker, died and dozens were injured.
Mr Opperman was held in the House of Commons along with other members of Parliament, and ushered out after 7pm.
The officer, who died in the attack, was named as 48-year-old PC Keith Palmer.
Mr Opperman said: “We walked past him every single day – it’s no different from a security guard that guards other people’s offices.
“It’s immensely shocking. These people are very brave.”
The MP travelled back to Hexham on Thursday and said he would go ahead with surgeries this weekend.
“Life must go on,” he said.
“The terrorist wins if we try and change the way we live.”
Hexham West Coun. Derek Kennedy caught the tube from Westminster just an hour before the incident. He called the attack “horrendous.”
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