Washington: A 92-year-old woman from the US state of Arizona killed her son in order to avoid being sent to an assisted living facility.

"You took my life, so I'm taking yours," Anna Mae Blessing said as deputies escorted her from the apartment in Fountain Hills she shared with her 72-year-old son and his girlfriend.

Court records show Blessing had been contemplating her son's intentions to put her in an assisted living facility for several days prior to the shooting on Monday, reports AZ Central newspaper.

Blessing told deputies her son wanted her to leave because she "had become difficult to live with".

Blessing reported hiding two pistols in the pockets of her robe before confronting her sleeping son, the records said.

She fired one of the pistols multiple times, striking and killing her son before pointing the gun at his girlfriend, who wrestled away the firearm and threw it into a corner of the room.

Officials said Blessing faces charges of first-degree murder, aggravated assault with a deadly weapon and kidnapping. Her bail bond was set at $500,000.