Major landmarks in British capital London were illuminated in the colours of the French flag Sunday, in a show of solidarity with France, where terrorist attacks last week killed 17 people.

Trafalgar Square, the National Gallery and Tower Bridge were all lit in blue, white and red to pay respect to the victims of the fatal attacks, Xinhua reported.

Thousands of people, with many holding placards, pencils, French flags and portraits of the victims, gathered at the Trafalgar Square for a “unity rally” as a massive march was taking place in Paris to protest against terroism and racism.

“Thanks to all at London’s gathering of solidarity with Paris. Cities of freedom (are) united in the fight for that freedom,” said London Mayor Boris Johnson, who was present at the rally.

He tweeted that the lighting was just “one example of London’s incredible response to (the) events in Paris”.

British Deputy Prime Minister Nick Clegg and the French Ambassador to Britain, Sylvie Bermann, also joined the crowd at Trafalgar Square, where a vigil was held to offer tribute to the victims.

British Prime Minster David Cameron and the Labour Party leader Ed Miliband, both travelled to Paris Sunday to join other world leaders in an unprecedented march against extremism, which reportedly saw about 1.5 million people taking part.

German Chancellor Angela Merkel, British Prime Minister David Cameron, Italian Prime Minister Matteo Renzi, European Commission President Jean-Claude Juncker, European Parliament President Martin Schulz, European Council President Donald Tusk, Israeli Prime Minister Benjamin Netanyahu, Palestinian leader Mahmoud Abbas and Turkish Prime Minister Ahmet Davutoglu were among the leaders present at the march at Paris.

“People wanted to show real solidarity with the victims, and that’s why it was right to come to show solidarity with the French people after these appalling attacks, but also to recognise (that) we face the same threat,” Cameron said after the rally.

“We have to confront it in our own country — keeping our security strong, but also taking on this poisonous narrative, that is radicalising young minds, wherever we find it. And that work continues,” Cameron added.