The shooting happened in the 9200 block of Pentland Street just after 7 a.m. on New Year's Day. Deputies went to the home after receiving a call about a possible domestic violence incident involving a shooting.
Investigators say 28-year-old Justin Joseph shot and killed 27-year-old Jeanette Gallegos before killing himself.
According to a report published by the Pasadena Star-News, Gallegos had three children between the ages of 5 and 11. They reportedly ran out of the house unharmed the moment police arrived.
Joseph was not the father of the children, according to reports, and was Gallegos' boyfriend.
The Pasadena Star-News said one of the children made the 911 call early Saturday morning.
A GoFundMe account has since been created to help the family of Gallegos' with funeral expenses.
The incident remains under investigation.
Anyone with information is urged to contact the Los Angeles County Sheriff's Department's Homicide Bureau at 323-890-5500. You can also submit information anonymously by calling Crime Stoppers at 800-222-TIPS (8477).