A 13-year-old boy was knocked unconscious following an attack at Preston bus station, say police.
Another boy in his early teens was also punched during the incident which happened on August 19 at around 7.15pm.
Police have now launched a CCTV appeal to try to trace two men they think may be able to help them with their enquiries.
A police spokesman said: "We would like to speak to [these two males] following an assault which took place at Preston Bus Station on two males in their early teens.
"If you are able to identify either of these males or have any information which may assist please contact police."
Anyone with information can call 101 or email firstname.lastname@example.org quoting crime reference SA1713133.