• Veteran Conservative MP David Amess, 69, was talking with voters at a church when he was stabbed to death.
• Police said they arrested a 25-year-old suspect and were investigating "a potential motivation linked to Islamist extremism".
The fatal stabbing of British lawmaker David Amess was a terrorist incident, police said Saturday, as MPs pressed for tougher security in the wake of the second killing of a UK politician while meeting constituents in just over five years.
Veteran Conservative MP David Amess, 69, was talking with voters at a church in the small town of Leigh-on-Sea east of London when he was stabbed to death on Friday.
Police said they arrested a 25-year-old suspect and were investigating "a potential motivation linked to Islamist extremism".
Police have said the investigation is in the "very early stages", though multiple UK media outlets, citing sources, reported that the suspect was believed to be a British national with Somali heritage.
The Sun tabloid reported that the attacker stabbed Amess multiple times in the presence of two women staff, before sitting down and waiting for police to arrive.
Police said they believed the attacker acted alone and carried out searches at two addresses in the London area.
Prime Minister Boris Johnson visited the scene to pay his respects on Saturday, laying floral wreaths outside the church with the leader of the opposition, Labour leader Keir Starmer in a rare show of unity, along with the Speaker of the House of Commons Lindsay Hoyle and Home Secretary Priti Patel.
Members of the public also came to lay bouquets next to the police tape surrounding the crime scene.
One bouquet enclosed a handwritten note saying: "RIP Sir David. You did not deserve this."
Britain's politicians were stunned by the highly public attack, which recalled the murder of a pro-EU lawmaker ahead of the Brexit referendum.
In June 2016, Labour MP Jo Cox was killed by a far-right extremist, prompting demands for action against what lawmakers said was "a rising tide" of public abuse and threats against elected representatives.
Home Secretary Patel on Friday ordered police across the country to review security arrangements for all 650 MPs.
At the same time the interior minister insisted the attack would not stop MPs from holding face-to-face meetings with residents in the areas they represent.
"We will carry on... We live in an open society, a democracy. We cannot be cowed by any individual," she told Sky News after the wreath-laying.
House of Commons Speaker Hoyle promised no "knee-jerk reactions" but told Sky News: "We will take further measures if we need to".
Tobias Ellwood, a Conservative MP who tried to save a stabbed police officer during a 2017 terror attack near the Houses of Parliament, on Twitter urged "a temporary pause in face to face meetings" until the security review is complete.
- Increasing threats -
MPs and their staff have been attacked before, although it is rare.
But their safety was thrown into sharp focus by Brexit, which stoked deep political divisions and has led to often angry, partisan rhetoric.
Cox's killer repeatedly shouted "Britain first" before shooting and stabbing the 41-year-old MP outside her constituency meeting near Leeds, northern England.
A specialist police unit set up to investigate threats against MPs in the aftermath said 678 crimes against lawmakers were reported between 2016 and 2020.
Most (582) were for malicious communications, although other crimes included harassment (46), terrorism (nine), threats (seven), and common assault (three).
Separate figures indicated a sharp rise in reports since 2018, including three threats to kill.
Amess himself wrote about public harassment and online abuse in his book "Ayes & Ears: A Survivor's Guide to Westminster", published last year.
"These increasing attacks have rather spoilt the great British tradition of the people openly meeting their elected politicians," he said.
MPs have had to install security cameras and only meet constituents by appointment, he added.
MPs' staff have also spoken of bearing the brunt of abuse.
"I would get in and all I would do is go on Facebook and report death threats and delete them," said Jade Botterill, who worked for senior Labour MP Yvette Cooper from 2013 to 2019.
"I reckon I reported over 1,000 death threats," she said, adding it caused her sleepless nights and fears she would be attacked.