The woman who fatally shot a Dallas officer Saturday before killing herself told a 911 operator she killed him before he could hit her again, police said, reports the Dallas Morning News.

Otto Machelle Thomas, 42, called 911 about 6:15 p.m. from the officer's apartment to report she had just committed murder, Assistant Chief Randy Blankenbaker said.

Blankenbaker said Thomas told 911, "He was getting ready to hit me again and I just went off. I killed him because he was going to hit me again."

Thomas said that the officer had been her boyfriend and that she needed someone to come get her 6-year-old daughter, he said.

When police arrived, Thomas would not come out and police heard a gunshot, Blankenbaker said. Police found Thomas and the officer dead in the apartment. The girl was unharmed.

There had been no previous disturbance or domestic violence calls involving the couple, Blankenbaker said. Tuttle's wife told KXAS-TV (NBC5) that she and her husband were separated and he had been a great father to their 10-year-old son.