Singer Leona Lewis was punched by a fan while signing copies of her autobiography, Dreams, at a London bookstore Wednesday.

Lewis, 24, had been signing autographs at the bookstore for about 90 minutes when "a guy came up and punched her to the side of the head," the pop star's spokesman tells the BBC. Though she didn't need to go to the hospital, Lewis was "understandably badly shaken," her spokesman says.

According to an eyewitness at the store in Picadilly, "[the attacker] walked up there with the book, she signed it and, as she looked up, he just punched her."

"She was running out with her hand over her eye," the eyewitness adds, "and I just saw a man on the floor."

Waterstone's bookstore released a statement about the incident, saying they were supporting any police investigation and thanking Lewis for her professionalism. While the singer did not need to go to the hospital, she did pull out of a scheduled appearance on BBC's The One Show that night.

Lewis recently released a new single, "Happy," from her sophomore album, Echo, due Nov. 17.