Justin Bieber is wanted for questioning by police after a scuffle with a photographer on Sunday.
The Canadian singer reportedly grew angry when a photographer tried to take pictures of him with his girlfriend Selena Gomez at a shopping centre in Calabasas, California.
Sheriff's Lt. Robert Wiard said the photographer called police on Sunday and complained of pain to his chest. He said the photographer had been taken to hospital to be treated, but has been released.
Lt. Wiard said that 19-year-old Bieber left the scene of the scuffle before police arrived, and that they wanted to hear his side of the story.
The celebrity news website TMZ reports that witnesses said that the photographer was blocking the path of the singer's car. Bieber allegedly got out of the car to ask him to move, and when he didn't a scuffle ensued.
The website also reports that the photographer filed a police report and that the incident is being investigated as suspected criminal battery.
A tweet from Bieber's official account says its will "focus on the important stuff - the music" - a possible reference to the incident.
Photographs from the scene claim to show Bieber's girlfriends Selena Gomez comforting him as he puts his shoes back on.