Ruiz went outside and saw the woman screaming at her son-in-law, who was working on a truck across the street. They ran inside. Seconds later, Ruiz said, she heard more screams.
The man ran back outside, Ruiz said, frantically trying to dial his cellphone.
"Oh my God," he said. "Oh my God."
Ruiz went to his mother-in-law, who was on the phone with police.
"She killed the babies," the woman said.
Residents of an unincorporated neighborhood near Torrance described the chaotic scene Tuesday night, when a 30-year-old stay-at-home mother was arrested on suspicion of killing her three daughters.
Law enforcement officials identified the girls as 2 1/2-year-old Sophia, 16-month-old Yazmine and Zenia, who was 2 months old.
Investigators said Carol Coronado, 30, was "covered with blood" when her mother found her lying on a bed next to the girls' bodies. Coronado, who was half-clothed, also had self-inflicted stab wounds, said sheriff's Lt. Dave Coleman.
There was evidence to suggest Coronado used a knife in the attack, Coleman said, but it was unclear what other injuries the children might have suffered.
"There was evidence of stab wounds," Coleman told The Times on Wednesday. "We still haven't established how they died exactly yet. But there were stab wounds."
Coroner's officials said autopsies were scheduled to be performed Thursday.
When police led Coronado out of the house in the 1000 block of West 223rd Street, she was handcuffed and covered in a blanket, said neighbor Ashley Madrid.
"She had a zoned-out look and was just looking down," Madrid said. "She had dry blood smeared on her face and legs."
Coronado's husband, Madrid said, collapsed in the street as sheriff's deputies escorted him to a patrol car.
"It was very horrible to see," she said. "Very heartbreaking."
"We still haven't determined a reason," Coleman said, later adding, "Obviously we're going to have to delve into her mental state."
Coronado served in the military as a young woman, Coleman said, but left after a short stint because of medical reasons.
In a brief interview with The Times, Coronado's father-in-law said there were no obvious red flags before the killings. Rudy Coronado, 67, said his daughter-in-law was "trying to go to school and take care of the kids."
Rudy Coronado said his son called him with the news Tuesday night. He was so quiet, he said, "he couldn't say anything."