One woman was killed and five others were injured in a mass stabbing in central London's Russell Square on Wednesday night, police said.

According to London Metropolitan Police, the suspect, a 19-year-old man was arrested at 10.39 p.m., after a Taser was discharged by an officer, the BBC reported. 

Police said mental health was a "significant factor" in the incident that took place in a busy area close to the British Musem and home to many hotels and restaurants popular with tourists.

“Early indications suggest mental health is a significant factor in this case and that is one major line of inquiry," the Guardian quoted Mark Rowley, an assistant commissioner in the Metropolitan police and Britain's most senior counter terrorism officer as saying early Thursday morning.

“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," he added.

Police were called at 10.33 p.m. on Wednesday night to reports of a man injuring people with a knife.

The victim, a woman in her 60s, was treated at the scene but was pronounced dead later, the BBC said.

Police said there would be an increased police presence on the streets of London from Thursday morning “for reassurance and safety”.

The incident came after authorities earlier on Wednesday announced London would increase its presence of armed police after recent terror attacks in Europe.

In the terror attacks of July 7, 2005, the underground subway line running close to Russell Square was hit by the most devastating of the four bombs that killed 52 people and injured over 700 others.