South Wales Police are appealing for witnesses after an incident on Broad Street, Barry, in the early hours of Sunday, 26 July.
Officers were called at around 1.30am following reports of an affray in the street.
Images and videos of the disturbance have since circulated on social media, and investigators are keen to speak to anyone who was in the area at the time or who may have captured footage that could assist the inquiry.
Police are urging anyone with information to come forward and quote reference 2600240678.
Reports can be made online via the South Wales Police website, by calling 101, or anonymously through Crimestoppers on 0800 555 111.

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