UPDATED: City centre cordoned off in two separate incidents

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.

He said: "All I'm aware of is that there was a reported bomb in the building and the police have been called as a precautionary measure to make sure the building is safe and secure.

"Obviously our concern is for the safety of our residents and the homeless people, so the building has been cordoned off and the police are investigating, and making sure the building is safe to get back into."

Updated 4.15pm: 

A South Wales Police spokesperson has confirmed a 44-year-old man was arrested at the Media Wales building at 3.40pm.

Updated 3.55pm:

We've been told the police took down cordons at Media Wales, currently trying to confirm.

Updated 3.40pm:

Police are still negotiating with the man on the roof of the Media Wales building.

Updated 3.40pm:

Re: the threatening phone call incident at The Huggard Centre earlier this afternoon, South Wales Police say a 19-year-old man has been arrested.

Updated 3.16pm:

At around 2pm today, armed South Wales Police officers flooded the Huggard Centre on Custom House Street, Cardiff City Centre, following a threatening phone call.
 
A police spokesperson said the premises have been cleared and are being searched.

South Wales Police confirmed there was no bomb scare, but armed officers are in attendance as a precaution.

In a separate incident, police have responded to calls a man is on the roof of the Media Wales building in Park Street, threatening to jump off. He is believed to be a member of staff.