A 19-year-old man has been arrested on suspicion of murder after a knife attack in central London in which a woman was killed and five other people injured.
Counter-terrorism officers are supporting the investigation into the incident, while Scotland Yard said early indications suggest mental health "was a factor".
Armed officers raced to the scene in Russell Square on Wednesday night following reports that a man armed with a knife was targeting people.
A woman, believed to have been in her 60s, was pronounced dead at the scene, while two other women and three men were hurt.
A Taser was discharged during the arrest of the suspect. He received hospital treatment and was then taken into custody at a police station in south London.