LONDON — A Conservative Party lawmaker was stabbed to death on Friday afternoon as he was meeting with local constituents in southeast England, an attack that has rattled the country’s political establishment.
Members of Parliament identified the lawmaker as David Amess, 69, a long-serving member of the House of Commons.
“Rest In Peace Sir David,” the education secretary, Nadhim Zahawi, wrote on Twitter.
The speaker of the House of Commons, Lindsay Hoyle, said in a statement, “I am shocked and deeply distressed by the killing of Sir David Amess,” adding that over almost four decades in government Mr. Amess had “built a reputation for kindness and generosity.”
“This is an incident that will send shock waves across the parliamentary community and the whole country,” Mr. Hoyle said.
Mr. Amess, a hard-line critic of the European Union and a supporter of Brexit, is the second lawmaker to be killed in such an attack in little more than five years. In 2016, Jo Cox, a Labour lawmaker, was killed when a right-wing extremist targeted her outside a meeting with constituents. Stephen Timms, another Labour lawmaker, was stabbed in 2010.
The Essex police confirmed in a statement that a man had been killed in an attack in the area but did not name Mr. Amess. The police said that a suspect had been arrested on suspicion of murder, and that officers had recovered a knife at the scene.
Mr. Amess, had been scheduled to hold a meeting with voters at the Belfairs Methodist Church in a district of Southend, Leigh-on-Sea, east of London, where the attack is reported to have occurred. Photographs taken at the scene showed a number of emergency responders and a cordoned-off area around the church. Local news outlets reported that an air ambulance had landed nearby.
In their statement, the police said that officers had responded to reports of a stabbing in Eastwood Road North, where the church is, shortly after 12:05 p.m.
“We are not looking for anyone else in connection with the incident and do not believe there is an ongoing threat to the wider public,” the police said. They added that they wanted to thank the people who had alerted them to the incident so quickly and appealed for further information from potential witnesses or from anyone who had any relevant CCTV or other footage.
Lawmakers from across the political spectrum, and other prominent Britons, reacted with horror to the news.
On Twitter, Carrie Johnson, wife of Prime Minister Boris Johnson, wrote: “Absolutely devastating news about Sir David Amess. He was hugely kind and good. An enormous animal lover and a true gent. This is so completely unjust. Thoughts are with his wife and their children.”
“Heartbroken,” wrote Tracey Crouch, a fellow Conservative lawmaker. “I could write reams on how Sir David was one of the kindest, most compassionate, well liked colleagues in Parliament. But I can’t. I feel sick. I am lost. Rest in Peace. A little light went out in Parliament today. We will miss you.”
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 maintain contact with voters, the surgeries can also make lawmakers vulnerable to security breaches.
A father of five, Mr. Amess first entered Parliament in 1983, when Margaret Thatcher led the Conservative Party. He initially represented the seat of Basildon in Essex, where his election consolidated a groundswell of support for the Conservatives in that area. He switched constituencies to Southend West in 1997, a seat that he held in every subsequent general election.
Raised as a Roman Catholic, Mr. Amess was known as a social conservative, a campaigner against abortion and a staunch supporter of the British monarchy. He was also known for his campaign to win city status for the seaside town of Southend. Among his principal causes was 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.
“Attacking our elected representatives is an attack on democracy itself,” he wrote. “There is no excuse, no justification. It is as cowardly as it gets.”