Deja Taylor's son brought her gun to school in the southern US state on January 6 and shot his elementary school teacher.
Firearms are most common weapon used in homicides of spouses, intimate partners, children or relatives in recent years, according to data from the federal Centers for Disease Control & Prevention.
At least 22 dead in Maine shooting as police hunt for 'person of interest'; residents ordered to shelter
Robert Card, who was trained as a firearms instructor at a US Army Reserve training facility in Maine, is the person of interest. He had been committed to a mental health facility for two weeks.
John Snowling, a retired police sergeant, was married to Marie for more than three decades, They have two adult children. He killed three people, including his wife's dining companion and a man.
The case shocked the country and renewed national debates about gun policies and race in America.
The initial emergency call from hospital security reported "someone visiting a patient verbally threatened hospital staff" before the shooting, OregonLive/The Oregonian reported.
Police Chief Troy Finner said officers found six people shot following a disturbance inside the club that spilled out into the parking lot.