By Laila Kearney

NEW YORK (Reuters) - An American woman killed in a knife attack in London on Wednesday night was the wife of an eminent psychology professor at Florida State University (FSU), the university said in a statement on Thursday.

Richard Wagner, the Robert O. Lawton Distinguished Professor of Psychology, and his wife were in London where he taught in the summer session at FSU's London Study Program, it said. Police in London have said she was in her 60s.

FSU did not name Wagner's wife, but Florida Governor Rick Scott identified her in a tweet as Darlene Horton and said that he and his wife were praying for her family and loved ones.

Horton died at the scene and five people were injured when a 19-year-old man with suspected mental health problems went on a rampage with a knife in central London's Russell Square. Police have said there was no evidence the attack was terrorism related.

"There are no words to express our heartache over this terrible tragedy," FSU President John Thrasher said in the statement.

FSU said its students had already left the program for the summer and that none were involved in the incident. James Pitts, director of FSU International Programs, said in the statement the couple had planned to return to Tallahassee on Thursday.

(Reporting by Laila Kearney in New York; Additional reporting by Letitia Stein in Tampa; Writing by Daniel Wallis; Editing by Steve Orlofsky)