Police say it was a violent dispute that left the girl dead. Police say the woman, Blair Stockdill, 25, was apparently arguing with her ex-boyfriend. He was stabbed several times.
Police had to smash a patio wall to gain entrance to the apartment at about 11:30 a.m. Monday.
Neighbors say they first heard two people fighting. The man was bloody, his arms cut from being stabbed with a knife.
"So we just heard the screams and that was about it," said Patricia Payne, a neighbor.
Neighbors called 911. When police responded to the apartment they found the man and the woman still arguing. Officers had to smash the patio to get in.
"A male had been stabbed numerous times. He was stabbed in the arms. Ambulance personnel took him away. We're interviewing him," said Ventura Police Sgt. Jack Richards. "There was a female that we took into custody that could be involved. And in searching and securing the residence, once we secured that situation, we located a young child -- not giving the age yet -- deceased in the residence."
Police later revealed the girl, 8, is Stockdill's daughter. She recently regained legal custody of her daughter, according to Ventura Police.
Ventura Police said the cause of the girl's death was not released pending an autopsy.
"It's just terrible," said Payne. "It's just terrible. To have somebody, just a little girl, right around the corner from you murdered like that. It's awful."
Some neighbors say they saw the woman and the girl in the neighborhood, and there was something unusual.
"Her mother seemed a little 'off,'" said neighbor Janet Ryan. "Just a little out of it, not really there. And it's just been like that in the last couple months."
One woman who lives upstairs from the apartment says the little girl played with her children all the time.
"She was so outgoing," said neighbor Brittany Duquidwai. "I mean, she would talk to everybody, she was just full of life, considering what we now know of her exposed in her home life. I mean, she was a very outgoing little girl, just playing with everybody, talked to everybody. I just can't even believe that she's gone."
The man is hospitalized with stab wounds. The woman remained in custody Monday. Detectives were interviewing her, trying to piece the story together.
If you have any information about this crime, you can make an anonymous call to Crime Stoppers at (800) 222-TIPS.