The PSNI is negotiating with a man at the GP Out of Hours surgery at Craigavon Area Hospital.
The on-going incident started this morning with the police and NI Fire and Rescue Service attending.
It is understood there are concerns for the safety of a man attending the service.
Traffic diversions are in place.
In a message on Twitter the Southern Health Trust said: “There is an incident ongoing on the Craigavon Area Hospital site.
“Traffic restrictions are in place.
“Emergency services are at the scene.
“We will keep you updated.”