TERROR: American Woman Stabbed to Death by ‘Somali’ in London

London (CNN)Police said Thursday the victim of a fatal knife attack in central London overnight was an American woman in her 60s and ruled out terrorism as the likely motive.

London Metropolitan Police Assistant Commissioner Mark Rowley said authorities’ main line of inquiry was around mental health issues. Officials briefed on the investigation had earlier told CNN they believed the stabbing at Russell Square was a terror attack based on initial evidence.

Police said it had arrested a 19-year-old man on suspicion of murder. The suspect is a Norwegian national of Somali origin, Rowley said, and “so far we have found no evidence of radicalization.”