Investigators are saying a broken relationship left a bullet in the door of the victim's apartment late Wednesday night.
Police were called to the Chalet Apartments near Interstate 35 and NE 21.
Police say they're looking for at least three suspects, and one of them is the girlfriend of the victim's daughter.
According to police, the victim's daughter recently ended a relationship with her girlfriend.
The now, ex-girlfriend showed up at the victim's apartment to get some of her things with a couple of male friends.
"At one point, it was reported they were trying to get in the apartment. The mother was holding the door shut, and that's when one round was fired through the door, struck her and they all fled the scene," Moore police Sgt. Jeremy Lewis said.
The bullet went through the victim's arm and lodged in her chest.
Investigators say she was immediately taken to OU Medical Center for surgery in serious condition.
Police are still searching for suspects.