Wayne Boylan (37) died from gunshot wounds sustained during an incident, which occurred at a house in Lower Dromore Road at around 7.30pm.
Detective Chief Inspector Geoff Boyce said: “It’s understood two men entered a property on Lower Dromore Road at around 7.30pm last night and fatally shot Mr Boylan.
“A 21-year-old woman also sustained gunshot injuries and was taken to hospital where her condition this morning is believed to be critical.
“A motive for the incident has not yet been established and I am appealing for information. I would particularly like to hear from anyone who was in the area last night and who may have seen two men or any vehicles fleeing from the scene immediately after the shooting.
“Major Investigation Team detectives can be contacted by calling 101, quoting reference 1115 18/01/19.”
Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100 per cent anonymous.
Detectives last night launched a murder investigation following the fatal shooting.
The injured woman meanwhile was taken to Daisy Hill Hospital but has since been transferred to the Intensive Care Unit at the Royal.
South Down Sinn Fein Assembly member Sinead Ennis last night said that the community of Warrenpoint were “shocked and stunned” by what had unfolded.
“Our first thoughts are with the family of the victim,” she said.
“The PSNI have the area sealed off and I would appeal to anyone with information to bring it forward to assist the investigation.”