Six people are in hospital including three people with stab wounds after a "violent incident" in Cardiff city centre.
Parts of Queen Street and Newport Road were cordoned off by a large police presence on Saturday evening.
Officers received "multiple" reports of a violent incident at around 9.50pm, South Wales Police said.
Six people have since been taken to or have self-presented at the University Hospital of Wales.
One person is said to be in a serious condition with head injures, and three others are believed to have sustained stab wounds.
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Two people have been arrested on suspicion of violent disorder in connection with the incident and are currently in custody in Cardiff Bay.
Investigations are underway and anyone who witnessed the incident or events prior to or after it, are urged to contact police via 101, quoting occurrence 2000424668.