Halifax Regional Police said they were negotiating with a man who was armed with a knife at a Dartmouth apartment complex on Thursday evening.
Police said they responded to calls about a man causing a disturbance around suppertime at Alderney Manor, a multi-storey complex in downtown Dartmouth.
The man refused to open the door to a unit and told officers he was armed with a knife, police said in a statement.
A number of officers arrived on the scene, including crisis negotiators. Eyewitnesses told CBC News that more than a dozen officers, some wearing armour, were taking part in the operation. Police asked people to avoid the area.