A woman has died and five other people were injured in a knife attack in Russell Square, central London.
Police were called at 22:33 BST on Wednesday to reports of a man injuring people with a knife.
One of the victims, a woman in her 60s, was treated at the scene but was pronounced dead a short time later.
A 19-year-old man was arrested at 22:39 after a Taser was discharged by an officer.
Two other women and three men received various injuries in the attack, Scotland Yard confirmed later.
The Met’s assistant commissioner for specialist operations, Mark Rowley, said the force’s homicide command was leading the investigation into the attack, with support from the counter-terrorism unit.