Leona Lewis is feeling anything but “Happy.” The British pop star was attacked by a man at her book signing in the U.K. on Wednesday.

The “Bleeding Love” singer was signing copies of her new autobiography Dreams and posing for photos with fans at Waterstone’s Piccadilly bookstore in London when a man came from the line and hit her on the side of her head.

“My brother saw the whole incident. [The attacker] walked up there with the book, she signed it and, as she looked up, he just punched her,” one fan at the scene told BBC News. “[My brother] actually heard the impact.”

Another eyewitness added: “She was running out with her hand over her eye and I just saw a man on the floor.”

Security hauled the 29-year-old man away. He was later arrested by police on suspicion of assault and is being held in custody. Lewis visited a doctor as a precaution.