Teen pleads guilty to killing American woman in London

Zakaria Bulhan, 19, pleaded guilty at London's Central Criminal Court to manslaughter due to diminished responsibility. Darlene Horton, 64, of Tallahassee, Florida, was killed in the August 2016 attack.

At Monday's hearing, Bulhan also admitted five counts of wounding with intent to cause grievous bodily harm. "Without warning or provocation, the man stabbed six people in quick succession, saying nothing to any of them, moving on after each stabbing towards his next victim," prosecutor Mark Heywood said.

Bulhan had been due to stand trial on one count of murder and five counts of attempted murder.

"We have considered expert evidence from both prosecution and defense psychiatrists who have concluded that Bulhan was suffering from paranoid schizophrenia and experiencing a psychotic episode at the time. For that reason, we have agreed to accept Bulhan's guilty plea to manslaughter based on his diminished responsibility," the Crown Prosecution Service said in a statement.

Police said Bulhan is a Norwegian national of Somali origin. Norway's National Criminal Investigation Service said he had emigrated from Norway in 2002.

The attack sparked a major police operation and initially there were fears that it might be linked to terrorism. That was found not to be the case, but Bulhan still poses a significant threat to the public, police said.

"He clearly poses an enormous risk to the general public and I hope he can now get the help he needs," police Detective Inspector Tony Lynes said in a statement.

Darlene Horton, 64, was killed in the London knife attack in August 2016