Detectives have appealed for information and witnesses to come forward after the incident which was reported just before 9.25 pm on Friday night.
A child was in the house at the time of the burglary.
Three masked men forced entry to a house on Dunmore Road in Ballynahinch sometime between 6pm and when it was reported to police.
One of the two women inside the house, aged in her 30s, was assaulted and beaten with a baseball bat, sustaining injuries to her head and body.
Both women had their hands and feet tied with cable ties and both were locked in rooms in the house.
A young child who was in the house at the time was unijured. Both women and the child were taken to hospital.
Detective Sergeant James Johnston said: “The three suspects fled after ransacking the property.
“This must have been a terrifying and horrific ordeal for these women who have been left traumatised.
“Our enquiries are at an early stage, and I want to make a number of appeals today.
“Were you in the Dunmore Road area around this time last night, between 6pm and 9pm?
“Did you see any strange vehicles in the area?
“Did you seen three men in the area acting suspiciously?
“If you have information you believe may assist our investigation contact detectives in Ardmore on the non-emergency number 101, quoting reference number 1307 of 02/11/18.”
Alternatively information can be passed anonymously to independent charity Crimestoppers on 0800 555 111.