- Video: Motive unknown in stabbing murders
- More: Most Popular stories, videos and more
- More: Get breaking news alerts
Police believe the suspect simply walked into the home through an unlocked French door, attacking Davina Husted in the kitchen.
Her 9-year-old son reportedly saw the suspect enter the home, woke up his 11-year-old sister and ran to a neighbor's house.
Police initially thought the boy saw the attack, but sheriff's Sgt. Dave Murray later said the child ran into another room and didn't witness the killings, but did find the bodies.
Brock Husted was killed when he came to the aid of his wife, who authorities said was pregnant.
The search for the suspect has been concentrated on homeless encampments in the area, hoping to find any clues in the case.
Police said the suspect may have been wearing a black motorcycle helmet and a black jumpsuit at the time of the attack.
Neighbors said they were a happy family, and there were no signs of trouble before the incident.
"They were just really nice people," said neighbor Gina Haase. "It's a real shame."
Neighbors are worried because they do not know if the murders were random or if the family was targeted.
Authorities have no motive at this time, though they have not ruled out robbery.
Anyone with information about the murders is urged to call the Ventura County Sheriff's Department at (805) 477-7000.
The Associated Press contributed to this story.