London Mayor Sadiq Khan said on Thursday the safety of Londoners was his top priority and the public should remain calm and vigilant after a knife attack in central London.
One woman was killed and five others injured by a man with suspected mental health issues who went on the rampage with a knife in central London late on Wednesday, an attack police said could be linked to terrorism.
"The safety of all Londoners is my number one priority," Khan said in a statement.
"I urge all Londoners to remain calm and vigilant. Please report anything suspicious to the police. We all have a vital role to play as eyes and ears for our police and security services and in helping to ensure London is protected."
Londoners said they were nervous following the knife attack in central London.
"I think that the recent attacks in the rest of Europe have got everyone on high alert and I think that there is a lot more anxiety running through London right now," said Londoner Cal Strode.
London's Metropolitan police force had set up a cordon around the scene in Russell Square, near the centre of the city.
"It's such a busy area, it is right by Euston station. There must be thousands of people who pass through this area every day. I heard on the news this morning that the police response was quite quick I mean so that gives some comfort but yeah I'm shocked," Strode added.
Robert Burns, a teacher walking past the site of the attack on his way to work said he thought chances of being killed in an attack were slim.
"I look at the statistics - there are about two million people in central London at any one time. If one person is killed, the chances are it won't be me. It's the only way I can look at it and still feel comfortable," he told Reuters.
A woman in her 60s was treated at the scene of the attack but was pronounced dead a short time later.