Sandra Chico was initially detained as a "person of interest" after the grim discovery was made about 12:45 p.m. Monday in the 600 block of South Ferris Avenue. She was being held in lieu of $2 million bail, according to the Los Angeles County Sheriff's Department.
Chico's formal arrest was announced shortly after the county coroner's office released the names of the young victims:
Milan Mateas Rodriguez, a 1-month-old boy
Mason Mateo Rodriguez, a 3-year-old boy
Mia Camila Rodriguez, a 4-year-old girl
Sheriff's deputies found the children unresponsive and not breathing at the home. Deputies and paramedics attempted life-saving measures, but all three children were pronounced dead at the scene.
The causes of death have not officially been disclosed.
Investigators are not saying how the children died, but family members say Chico suffocated them and then tried to kill herself.
"Preliminary information revealed no prior reports of abuse or child neglect to this location or the involved individuals," the Sheriff's Department said in a statement.
The agency urged anyone with information about the case to call the sheriff's Homicide Bureau at (323) 890-5500. Anonymous tips may be provided to L.A. Regional Crime Stoppers at (800) 222-TIPS.
Chico is scheduled to appear in court Wednesday, authorities said.
The children's paternal grandmother said the father was at work during the incident. She also said Chico was dealing with some issues.
"I won't criticize her," the grandmother said in Spanish. "I wish her well. She is also a victim of her illness, which is depression. And even more so during these times that people couldn't go out. She never went out for anything."
Sheriff Alex Villanueva says there were no signs that there were problems at the Chico's East L.A. home.
"There was no forewarning of any kind. There was no repeated calls for service. DCFS was not involved. There were no allegations of child abuse," Villanueva said. "This was out of the blue, tragedy. I know the family has been shaken to the core."
Devastated neighbors continue to add to a growing memorial in front of the children's home.
"I knew her when the kids were born. They were always playing in the yard and on the trampoline," neighbor Jose Hernandez said. "The mom was always going to the market, mopping, cleaning. They were very active. I don't know what happened. It's a mystery."
A GoFundMe page has been established to help the family pay for the children's funeral expenses.