Story highlights Zakaria Bulhan, 19, pleaded guilty to manslaughter Monday

American tourist Darlene Horton, 64, was killed in the attack last August

London (CNN) A teenager has admitted killing an American woman and wounding five other people in a string of random stabbings in London.

Zakaria Bulhan, 19, has admitted stabbing a woman to death and injuring five other people in a knife attack in London last year.

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.

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