SEATTLE (AP) — Police say a woman stabbed an elderly couple in Washington state and set several fires in their home after they allowed her to camp in their garden over several weeks.

Police said the attack occurred Saturday at the home in Bellevue.

The Seattle Times said the couple — an 83-year-old man and a 76-year-old woman — were seriously wounded and taken to Harborview Medical Center with injuries considered life-threatening.

Seth Tyler, a Bellevue Police Department public information officer, said officers put out the fires and arrested a 40-year-old woman trying to leave the scene.

He said the woman had been living in a tent in the yard.

Detectives had not determined a motive and they did not name the couple or the woman.