Two youths, including a 12-year-old boy from Hove, have been arrested after a robbery in Lancing.
The victim was punched in the face several times and had his phone stolen before two good samaritans stepped in.
Sussex Police said: “Police are appealing for witnesses after a young man was robbed in Lancing.
“The 12-year-old victim was walking along the alleyway between Monks Recreation Ground and North Road about 5pm on Sunday 20 November when he was approached by a group of teenagers.
“He was punched to the face several times and had his phone stolen before two older boys attempted to intervene and the boy ran away.”
Investigating officer Detective Constable Sebastian Day said: “We’re very keen to speak to the two boys who intervened, as they may be able to provide valuable evidence.
“We would encourage them, or anyone else who saw what happened, to report it online at https://sussex.police.uk/contact-us/response-to-appeal or call 101, quoting serial 1095 of 20/11.”
A 17-year-old boy from Lancing, arrested on suspicion of common assault and two counts of robbery, has been bailed until Friday 30 December pending further inquiries.
A 12-year-old boy from Hove, arrested on suspicion of two counts of robbery, has been bailed until 29 December pending further inquiries.
