A woman was murdered and five others injured in a ‘horrific’ knife attack in Russell Square last night.

A 19-year-old man has been arrested on suspicion of murder as London Mayor Sadiq Khan appealed for calm and police presence has been increased on the capital’s streets.

Armed police reached scene within five minutes after numerous calls from the public alerted them to the knife-wielding man attacking people around Camden’s Russell Square just after 10.30pm.

Police discharged a Taser during the arrest but no shots were fired during the incident, the suspect is in custody after being treated at hospital.

London Ambulance Service pronounced the woman, believed to be in her 60s, dead at the scene.

The other victims, two women and three men, who were also attacked received various injuries and two remain in hospital while the others have been discharged.

Assistant Commissioner Mark Rowley, from the Metropolitan Police, said: “This was a tragic incident resulting in the death of one woman and five others being injured.

“Early indications suggest that mental health was a factor in this horrific attack. However we are keeping an open mind regarding the motive.

“As a precautionary measure, Londoners will wake up this morning to notice an increased presence on the streets of officers, including armed officers today.

“We would urge the public to remain calm, alert and vigilant.”

The Metropolitan Police Service’s Homicide and Major Crime Command is leading the investigation, supported by officers from the Counter Terrorism Command.

The Mayor of London, Sadiq Khan, said: “The safety of all Londoners is my number one priority and my heart goes out to the victims of the incident in Russell Square and their loved ones.

“I have spoken with the Commissioner, and the Assistant Commissioner, who have assured me that our police officers are working extremely hard to investigate exactly what has happened and to keep the rest of us safe.

“A man was arrested at the scene. Police have spoken to him and are seeking to establish the full facts including motives for this attack.

“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.

“Our police officers are doing an incredibly difficult job on our behalf and they have my full support.”

Anyone with information is asked to contact the incident room at Lewisham police station on 020 8721 4868 or if they wish to remain anonymous, Crimestoppers on 0800 555 111.