The attacks on London Bridge and Borough Market mark the second time the General Election has been disrupted by an act of terrorism.
It comes less than two weeks after the parties suspended campaigning following the Manchester attack in which suicide bomber Salman Abedi killed 22 people attending an Ariana Grande concert.
There was no immediate announcement whether there would be a further suspension following the latest incident – which came just days before voters are due go to the polls on June 8.
However some form of pause looks likely as the politicians and public alike come to terms with another act of horrifying violence on the streets of a major British city.
Only two months ago Westminster itself was the focus when – in an incident chillingly reminiscent of the latest events – 52-year-old Khalid Masood drove a car into pedestrians on the nearby bridge and then stabbed an unarmed policeman at the gates of the Palace of Westminster.
On being informed of the latest attacks, Theresa May, who had been out on the campaign trail, headed straight back to Downing Street to be briefed by security officials on the fast-moving developments.
The Prime Minister, who will chair a meeting of the Government’s Cobra emergencies committee on Sunday, expressed her “huge gratitude” to the police and ambulance crews who attended the scene.