Mental health issues were "a significant factor" in a London knife attack that killed one woman and injured five others, British police said. 
A 19-year-old man was arrested in Russell Square, in the city centre, which was cordoned off after the attack as police swarmed the area. 
"Early indications suggest that mental health is a significant factor in this case and that is one major line of inquiry," Mark Rowley, a senior police officer, said in a statement on Thursday. 
"But of course at this stage we should keep an open mind regarding motive and consequently terrorism as a motivation remains but one line of inquiry for us to explore," it added. 
Russell Square is a busy tourist area with a string of high end hotels and is also close to the British Museum and the University of London. 
A woman believed to be in her 60s was treated by paramedics at the scene but pronounced dead. Two women and three men were also injured but no details have been released about their condition. 
The arrested man is currently in police custody in hospital. 
In a statement on Thursday, London Mayor Sadiq Khan urged "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," he said. 
The threat level in Britain remains at "severe", its second highest level, meaning a strike is "highly likely". 
London police had already promised to deploy more armed offices after a spate of deadly attacks in other European countries. 
It said on Wednesday they would deploy an additional 600 armed officers across the capital to protect against the threat of attacks.

Source: QNA