Two boys were robbed in Bournemouth with both victims injured in the 'traumatic' attack.
Four men approached two teenage boys while they walked along Stirling Road in Winton at around 11:15pm on Friday March 22.
The attackers, who had just got off a bus, attacked the boys before demanding they hand over their mobile phone.
One of the boys, aged 15 had his mobile phone smashed, while the other, aged 13 - had his phone stolen along with a bank card.
Detective Constable Jon Sainsbury of Bournemouth and Poole CID said: "This has been a very traumatic experience for the two boys, and I am appealing for witnesses to assist with this investigation.
"One of the offenders is described as around six foot tall, well built, aged around 20 and wearing a grey hooded jumper."
Both victims received cuts and bruises, and no arrests have been made by police.
"Witnesses and anyone with information should contact Dorset Police on 101, quoting incident number 22:546.