According to investigators, the shooting occurred around 8 p.m. while the couple's two children were nearby inside their home in the 2800 block of Olive Street. At least 10 other people were inside the home at the time of the shooting.
Officials said the couple was arguing over the custody of their 11-year-old son and 6-year-old daughter when the suspect, 34-year-old Julio Ramon Solano, allegedly took out a gun and shot the woman in the upper torso. She was pronounced dead at a local hospital.
Solano initially fled, but he returned to the scene around 3 a.m. Monday and was arrested for the shooting.
Evelyn Tinoco, a witness, said she heard about three gunshots and rushed outside. She saw the woman stumble onto the street and collapse.
"The cops got here right away," said Tinoco. "That's really sad. I could imagine how hard it's going to be for their kids."
The children were not hurt. They were taken into the custody of the Los Angeles County Department of Children and Family Services.
Homicide detectives had Olive Street shut down for more than 12 hours, piecing the crime together. They brought in a K9 unit to sniff out clues and look for the murder weapon.