Shoppers walking through the centre, which is still open, will see Boots, Pep & Co, Goldsmiths, Eurochange and an ATM cashpoint between Pep & Co and Poundland have been affected from inside the centre.
Security and staff at stores affected are not commenting on the incident.
Other businesses may also have been affected.
The centre is still open to customers. Boots is open from its Gold Street entrance but closed to customers via the centre entrance.
More to follow.
Anyone with any information can call police on 101.