There's been an incident at Pulrose Post Office this morning (Tues).
It is thought to have involved someone attempting to demand money from staff.
Police say one person is in custody and is currently being questioned.
No further details have been released at the moment. Police say a statement will be released later today.
Pulrose Post Office has been closed until further notice.
Customers requiring benefits, pension and other services should go to the post offices at Regent Street and Anagh Coar.