Police investigating an attack on two men in a bookmakers where they were punched and slashed have released CCTV images of four men they wish to trace.
The attackers followed the two victims through Birmingham City University campus in Perry Barr to the bookmakers in the One Stop shopping centre.
When the two men refused to go outside and speak to the offenders, they were assaulted.
Police described the incident on 23 March as "unprovoked and violent".
Both victims were badly bruised with one receiving a cut to his cheek and the other a knife wound to the palm of his hand, West Midlands Police said.
Det Con Jennie Ellse, leading the investigation, urged anyone who recognises the men to contact police.
"No one deserves to be attacked in this way and we are determined to track these four men and bring them to justice," she said.
"We are keen to hear from anyone who can identify the four or may have been inside the shop at the time of the attack and who hasn't already spoken to us.
"This was an unprovoked violent attack, in broad daylight and in front of a shop full of customers."