The men entered a house in the Drumbeg South, Monbrief area shortly after 10pm on Thursday.
They sexually assaulted the mother, who was taken to a nearby hospital for treatment after the incident.
It is believed her children, aged three, two and seven months, were in the house at the time of the attack.
PSNI's Rape Crime Unit has released descriptions of two men in connection with the assault.
The first male, who spoke with a local accent, is described as being 6'6", of thin build and with large brown eyes.
He was wearing a dark V necked t-shirt, dark, tight fitted trousers and a snood pulled up to below his eyes.
The man was also wearing a khaki green monkey hat and may have had a tattoo of black writing on a green background on one arm.
The second male is described as 5'10", stout build and spoke with a local accent. He is described as wearing dark clothing and a balaclava pulled down over his face with eye holes cut out.