(CNN) A 92-year-old woman allegedly killed her son in Arizona because she did not want to be sent to an assisted living facility, authorities said.

Anna Mae Blessing was charged with first degree murder, aggravated assault and kidnapping after authorities found her 72-year-old son dead Monday at their home in Fountain Hills, Maricopa County Sheriff's Office said.

Blessing hid two pistols in the pockets of her robe and shot her son several times in his bedroom, the sheriff's office said in a statement.

Her son's girlfriend was also in the room and said she heard Blessing telling her son she was tired of the way he treated her, court documents said.

"From my understanding, she had thought about it for a few days because there was a dispute regarding her son wanting to put her in an assisted living home," Maricopa County Sgt. Bryant Vanejas told CNN affiliate KPHO.

Blessing then pointed the gun at her son's girlfriend, who struggled with her until she lost her grip of the gun. When Blessing pulled out the second pistol from her robe, her son's girlfriend also knocked it out of her hand, the statement said.

Once she was disarmed, Blessing sat on a reclining chair until deputies arrived and arrested her, officials said.

"As the suspect was being escorted from the residence, she made a spontaneous statement to the effect of 'You took my life, so I'm taking yours,'" court documents said.

Blessing moved in with her son and his girlfriend about six months ago, the affiliate reported.

She told deputies she had purchased one of the guns in the late 1970s and that her husband gave her the other pistol, court documents say.

Information on her attorney was not immediately available.