A teenager was stabbed in the spine with a broken bottle in Bristol over the weekend.
Another teenager suffered a broken jaw during the assault by a gang in the early hours of Saturday morning.
A gang of men in their early 20s approached a group from South Wales eating outside the Local Plus store on Baldwin Street, and attacked them "for no reason", say police.
As a result, two members of the group, both aged 19 and from South Wales, suffered serious injuries and were treated in the Bristol Royal Infirmary.
Both have now been released, although the student with the broken jaw has undergone surgery in Wales.
Police are appealing for witnesses, and officers are examining local CCTV cameras.