According to neighbor Ashley Madrid, Coronado's husband was outside working on his car when his mother-in-law discovered Coronado holding a knife surrounded by her dead children. Police were called shortly after 5 p.m. and quickly arrived on the scene.
"I saw when they were bringing him out," Madrid told local reporters. "He was crying. He was crying, 'She killed my daughters!' "
The girls were reportedly ages 3, 2, and 2-months-old.
Wrapped in nothing but a blanket, Coronado was first placed in a police car before being moved to an ambulance for care.
"She was full of blood on her face and arms," Madrid said.
Police have not yet confirmed witness reports that the children appeared to be stabbed and Coronado had attempted to kill herself. She is currently being held on suspicion of murder; the Los Angeles County Sheriff's department expects to formally charge her shortly.