South Wales Police officers were called to an incident on Broad Street, Barry, in the early hours of Sunday morning.
Photos circulating on social media showed a large presence of emergency services on the street.
A statement from the Police said: “South Wales Police responded to a report of a serious assault which occurred outside Bar Cocoa on Broad Street, Barry, shortly before 1am on Sunday, July 16th.
Firearms officers attended the scene alongside uniformed officers as a precautionary measure.
Two men were taken to the University Hospital of Wales with non-life-threatening injuries.
Two men, aged 21 and 29, were arrested in connection with the incident. The 21-year-old has since been released under investigation, while the 29-year-old was released on bail.
Enquiries are continuing and anyone who witnessed the assault but has not yet provided officers with an account is urged to contact 101, quoting reference 1700276022. Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.”