JLS sparked a frenzy as hundreds of screaming fans turned up to a catch a glimpse of their idols at a signing session.
The Everybody In Love quartet drew a crowd of more than 800 who queued to see them as they plugged their new book in central London.
The group were launching Just Between Us: Our Private Diary at Selfridges, ahead of its official publication date on Thursday.
At one stage an ambulance was called as a precaution after fears that a young fan was hurt, but she later proved to be fine.
Around 400 of those who had queued were able to attend the two-hour signing session.
The new book features behind-the-scenes photos of the band, who were runners-up in the 2008 series of The X Factor.