Russell Square stabbings: Darlene Horton named as victim
The US woman killed in a knife attack in central London has been named by police as 64-year-old Darlene Horton.
A man has been arrested on suspicion of murder after she was killed and five other people were injured in Russell Square.
Florida State University (FSU) has confirmed Ms Horton was the wife of psychology professor Richard Wagner.
Two other women and three men received various injuries in the attack, which happened near the Imperial Hotel.
A British man remains in hospital in a serious but stable condition while the others, an Israeli, and Australian and another American, have since been discharged.
After receiving treatment in hospital, the arrested man, who was detained in Bedford Place, is now in police custody in south London.
Norwegian police said in a statement the man had emigrated from Norway in 2002 and they were assisting London police.
The Met said they had searched an address in north London and another will be searched in south London.
The US ambassador to the UK, Matthew Barzun, said of the woman who died: "Heartbreaking news that a US citizen was killed in #RussellSquare attack. My prayers are with all the victims and their loved ones."
The couple had planned to return home to Tallahassee on Thursday.
US Secretary of State John Kerry described the attacks as a "horrific mass stabbing" and said he grieved for the victims.
He paid tribute to London's emergency services saying: "I particularly want to thank the first responders for their extremely effective and courageous efforts from to prevent this from having been worse."
And FSU President John Thrasher spoke of the university's "heartache" over the "terrible tragedy".
He said: "We are shocked that such senseless violence has touched our own FSU family, and we will do all we can to assist Professor Wagner and his loved ones, as well as his friends and colleagues in the Psychology department, as they mourn."
One of the victims of the Russell Square attacks was 18-year-old Israeli tourist Yovel Lewkowski.
She described what happened: "I saw that she [Darlene Horton] was bleeding and I looked at my arm and realised he had stabbed me also. I was in shock.
"She was still breathing when I saw her but after a few minutes it was too late and it was so awful to watch."
Police believe the attack on Wednesday was "spontaneous", with victims "selected at random".
Met Police assistant commissioner for specialist operations Mark Rowley said the investigation was increasingly pointing to the attack being "triggered by mental health issues".
He had earlier said the force was considering terrorism as a line of inquiry.
Mr Rowley, Britain's most senior counter-terrorism officer, told a press conference it had been necessary to consider "all possibilities" following recent terror attacks across Europe.
He added there would be an increased police presence on the streets in the wake of the attack - including armed officers - to "provide reassurance and safety".
Armed police entered the square shortly after 22:30 BST on Wednesday having received reports of a man attacking people with a knife.
They arrived within six minutes and chased the suspect, who eyewitnesses said had blood on his hands.
They said police ordered him to stand still but he kept running. He was then Tasered by officers.
Jodie Parry, who witnessed the events unfold from her hotel window, said she saw a man running down the street.
"I could hear the policeman screaming 'stop, don't move, don't go any further, just stay where you are', and he turned round and continued running," she said.
She added that the man was carrying a knife and had blood on his hands.
Paul Ó Geibheannaigh, who lives near to the square, said he had seen the body of the woman "on the pavement" and the area was surrounded by a "heavy armed police presence".
Met Police Commissioner Sir Bernard Hogan-Howe said the force's "swift response undoubtedly helped prevent more people from getting injured".
Earlier on Wednesday, Sir Bernard and Mr Khan had said there would be more armed police seen on patrol in London.
Sir Bernard announced the move to reassure the public and deter attackers following terror attacks in Europe.