Three men entered an address in Stockton with handguns and a knife and left with a handbag containing cash and other items.
Officers cannot confirm if the handguns were real or imitations but are appealing for witnesses.
The burglary took place at Westerdale Avenue in the Newham Grange area at about 0400 BST on Wednesday.
Police are looking for three men believed to be late teens to late 20s, all around 6ft (1.8m) tall.
The homeowner was in at the time but police say she was not injured during the incident.
Det Sgt Dave Harrison said: "This is clearly a distressing incident for the victim, but I want to reassure both them and members of the local community that we are doing everything possible to locate those involved and bring them to justice.
"We believe this is a completely isolated incident but to reassure members of the public further we have increased patrols in the area and our highly visible staff will be speaking to residents.
"We do need assistance from the people of Stockton; if anyone has seen anything or believes they can identify any of the men described I would urge them to get in touch."
The first man is described as being white, about 6ft tall with a thin face and fair complexion. He is said to be in his late 20s and wore a hooded top and tracksuit bottoms.
The second man is described as being black, over 6ft tall and skinny. He is thought to be in his late teens or early 20s and wore a dark hooded jacket.
The third man was white, about 6ft tall and wore a dark top.