Police say the incident at residential premises at the Granville Gardens area of Banbridge on Wednesday, January 2.
Sergeant Woods said: “At around 3:15 am, it was reported that a shot was fired through the front door of a house in the area.
“A female and two males were inside the house at the time of the incident, but there were no reports of any injuries.
“Damage was caused to the front door as a result of the incident.
“A car parked in the area had its rear screen smashed during the incident.
“Enquiries are continuing and we are appealing for anyone who saw anything suspicious in the area at the time of the incident to contact police on 101, quoting reference number 129 2/1/19.
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”