Darlene Horton (64) had travelled to UK with her husband for a summer course
A teenager has been charged with the murder of an American tourist following a mass stabbing in central London.
Zakaria Bulhan, 19, appeared in court today accused of murdering 64-year-old Darlene Horton.
He is also charged with the attempted murder of Martin Hoenisch, Lillie Selletin, David Imber, Bernard Hepplewhite and Yovel Lewronski.
Bulhan was remanded in custody following his appearance at Westminster Magistrates' Court.
Ms Horton, a university professor from Florida, had been just hours away from flying home with her partner when she was killed.
A British man who was stabbed in the stomach during Wednesday night's attack remains in hospital in a "serious but stable" condition.
An American man, an Australian man, an Australian woman and an Israeli woman were all discharged on Thursday.
Ms Lewkowski, who was visiting London from Tel Aviv, was stabbed in the upper arm.
The 18-year-old has written a Facebook post describing the moment Mrs Horton died in front of her.
"I'm not afraid, I want to keep going with the trip," she wrote.
"The last few hours have taught me to appreciate every second, I don't know whether to call it luck or fate, but no doubt it is some sort of miracle compared to the woman who stood right next to me and perished in front of my eyes: a matter of seconds, metres, breaths."
One of the tributes made to Ms Horton came from Florida State University president John Thrasher, who said: "There are no words to express our heartache over this terrible tragedy.
"We are shocked that such senseless violence has touched our own FSU family and we will do all we can to assist (Ms Horton's partner) Professor Wagner and his loved ones, as well as his friends and colleagues in the psychology department, as they mourn."
Another alleged victim, Mr Hoenisch - a retired firefighter from Las Vegas - wrote on Facebook: "Thanks to everyone for reaching out.
"We're still very saddened about the woman who was killed. Very unreal experience but we are still having an unbelievable time over here."
Bulhan is a Norwegian national of Somali origin who moved to the UK in 2002.
A neighbour of Bulhan in Tooting expressed shock at his arrest.
Parmjit Singh Bhamra described him as a "quiet, academic boy who was a bit of a loner". She said he liked football, basketball and music.