LONDON — In the wake of a deadly knife attack in central London, much of the discussion online has centred on the police citing mental health as a "significant factor" in the case.

Fears of terrorism are high as police have warned that a terror attack in the UK is almost inevitable following attacks in France and Germany.

But with police on Thursday saying there's no evidence of terrorist motives, people are discussing the contrasts between mental illness and terrorism and asking if it's dangerous to liken the two in the media.

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A 19-year-old Norwegian man of Somali descent has been arrested on suspicion of murder following the attack, which left an American woman in her 60s dead and injured five others. The attack happened around 10:30 p.m. Wednesday in Russell Square, an area of London popular with tourists and students. The British Museum is nearby, as are several hotels and university buildings.

"Early indications suggest that mental health was a factor in this horrific attack. However we are keeping an open mind regarding the motive," said Assistant Commissioner Mark Rowley of the Metropolitan Police.

Professor Sir Simon Wessely, the leading psychiatrist and president of the Royal College of Psychiatrists, told the Guardian that killings by people with psychiatric problems had been falling for the past 30 years. But he warned against looking for new powers to lock people up due to mental illness.

"We already have a very carefully thought-through Mental Health Act, which allows certain people to be detained and compulsorily treatment, in certain circumstances, for mental illness," he said. "But neither radicalism nor terrorism is a mental health diagnosis or disorder under the meaning of the Act."

He advocated improving services for alienated and mentally troubled young people and to decrease any alienation that would make them more vulnerable to radical influences.

Statistics from Time to Change, a programme to challenge stigmas regarding mental illness note that people with mental illnesses are more likely to be victims of violent crime than perpetrators.

The suspect's name hasn't been released. A witness told the BBC that the man was "screaming his guts out" as police tasered and detained him at the scene. Other witness accounts say the man was wearing a motorcycle helmet and black leather.

Some Twitter users warned against mixing up mental illness and terrorism.

worrying early conflation of mental illness and terrorism today in the news,

before any facts are actually known#RusselSquare — Rory Conn (@roryconn) August 4, 2016

You're not EITHER a terrorist or have mental health problems. Can we please understand this? #russellsquare — Felicity Morse (@FelicityMorse) August 4, 2016

It is just as dangerous to blame mental health as it is terrorism when facts are not known! Mental illness does not = killer #russellsquare — Jillibeanbaby (@jillibeanbaker) August 4, 2016

Mental health is such a vast spectrum, doesn't mean everyone is suicidal or homicidal. Stop the stigma #russellsquare #LondonStabbing — Angela Gooderson (@Angie_Gooderson) August 4, 2016

Others commented on what they perceived as the media and police using different terminology depending on the skin colour or religion of the attacker.

If #RussellSquare attacker is Black/Asian it will be deemed a terror attack. White, it'll be a mental health... https://t.co/HqPZBjJ6W6 — Mr Lee Jasper (@LeeJasper) August 4, 2016

Waiting to hear from the media if the #russellsquare incident is a terror attack or mental health, I presume it depends on his religion. — Snapchat: Dapper29 (@dapperlaughs) August 4, 2016

Amazing. Plod can spot "significant mental health issues" in someone whose ID they don't know, even while tasering him. #russellsquare — ((LibertarianRebel)) (@A_Liberty_Rebel) August 4, 2016

Others commented on the deployment of hundreds of armed police around the capital.

As all murderers have 'mental health issues', how about deploying 100s of shrinks instead of armed cops? #russellsquare — Brain Cocks (@horn_liam) August 4, 2016

#russellsquare if it's a mental health attack we shld invest in improving the support available for mentally ill ppl instead of the police — Enigma (@ahmed_shak_) August 4, 2016

#Russellsquare trended overnight and into the morning in the UK. There were many Islamophobic comments, which we haven't included here.

No matter what this investigation concludes, people remain jittery about attacks. Police urged Londoners to remain calm, alert and vigilant.

Russell Square is already a place associated with tragedy in London. It was the site in 2005 of the deadly blast during the 7/7 terror attack that killed 26 people when a suicide bomb was detonated on the Tube.