The State Fire Marshal’s Office says someone intentionally set a fire in a house in the Knox County town of Washington Thursday night.

A woman and three children in the house escaped without being injured by the fire, a spokesman for the Department of Public Safety said today.

The woman told investigators that a masked man with a gun entered the house on Bill Luce Road and confronted her. They struggled and he left after the smoke detectors went off, she said.

The woman said she received minor injuries from the fight but did not need to go to the hospital, police said.

The fire started in the basement and damaged that floor and caused smoke damage throughout the one-story ranch-stycle house.

The woman reported the fire at 9:45 p.m. Thursday after driving to a neighbor’s house with her children.