Two young boys featured on the YouTube website being goaded into fighting each other have been identified and are safe and well.
The 12 year olds were seen in footage posted on the video-sharing website trading punches, kicks and headbutts as a man filming the attack encouraged them.
A 21-year-old man, from Crawley, who was arrested yesterday on suspicion of aiding and abetting an assault remains in custody, a Sussex Police spokesman said.
Inquiries were continuing as the suspect faced further questioning today, the spokesman added.
Police said the images were "appalling" as they launched a joint investigation with officials from the West Sussex Young Persons' Services team.
Officers had appealed for information to identify the two boys and the amateur film-maker, who is heard sniggering behind the camera as the pair fight.
The Argus offered a £1,000 reward for a successful prosecution.
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