“A man more dedicated to his constituents you could not ever hope to meet,” Mr. Bowie wrote. “To have been attacked like this during a surgery is horrific. Praying for him and his family just now.”
Keir Starmer, the leader of the opposition Labour party, wrote, “Horrific and deeply shocking news. Thinking of David, his family and his staff.”
In Britain, most members of Parliament hold regular meetings, or surgeries, to allow their constituents to raise issues of concern. While the gatherings allow politicians to keep contact with their voters, the surgeries can also make lawmakers vulnerable to security breaches.
Mr Amess is a long-serving member of the House of Commons and first arrived in Parliament in 1983. Firmly on the right of the Conservative Party, he is a longstanding critic of the European Union and a supporter of Brexit.
Though he has never held high office, Mr. Amess has advanced a number of different causes during his political career, including animal welfare.
In 2016, Ms. Cox, died after being shot and stabbed by a right-wing extremist at a meeting in her parliamentary constituency in West Yorkshire. That attack took place in the prelude to the referendum on Brexit, and the assailant, Thomas Mair, an unemployed gardener, was sentenced to life in prison for the murder.
Ms. Cox’s husband, Brendan Cox, reacted to the news of the attack on Mr. Amess on Friday in a post on Twitter.