Armed police were called to a main road in Cardiff on Thursday night.
Officers were called to City Road just after 10pm on Thursday and were acting upon intelligence they had received.
It is understood a heavy police presence could be seen on City Road between Tavistock Street and Talworth Street.
A 29-year-old man from the Cathays area was arrested in connection with an assault in the Nottingham area.
“Armed officers were deployed as a precaution and to ensure the safety of the public and police officers.”