A Florida woman fatally shot her daughter while answering the door, thinking the person knocking was a boyfriend with whom she had just argued, police say. Anita Bing, 52, told Winter Haven police she accidentally shot her daughter, Ruby Bing, 25, when she opened the front door of her home with "a baseball bat in her left hand and a .22-caliber pistol in her right hand," CNN reported Tuesday. Witnesses said they heard a shot and saw the mother cradling her daughter in her arms, crying "Baby girl, don't die." Anita Bing was arrested and charged with second-degree murder. She also was charged with child abuse without great bodily harm because her daughter was holding her 4-month-old infant when she was shot. The baby was not injured. Ruby Bing, who police said was shot in the upper chest, died at the scene. Bing told police she had gotten into an argument earlier in the day with her boyfriend, James Lane. During the argument, Bing said, Lane threatened to kill her. When she heard knocking on the door, Bing said she armed herself because she thought Lane had returned.