Updated 5.45pm:
The statement from South Wales police is currently:
Officers responding to a threatening telephone call in Cardiff arrested a 19-year-old man for malicious communications.
We are yet to confirm this was the man arrested on St Mary Street earlier today, but it seems likely. We are unaware of any other arrests related to this incident.
Updated 4.55pm:
We interviewed Richard Edwards, who works in the Huggard Centre, about an hour ago.