Among those killed in the "horrific massacre" were a 17-year-old mom and a 6-month-old baby, Tulare County Sheriff Mike Boudreaux told reporters. Both were shot in the head, he said.
"We do have survivors," the sheriff said, adding that it's not yet clear how they survived.
The Sheriff's Office said it happened shortly after 3:30 a.m. Callers initially thought it was an active shooter situation because of how many shots were fired.
Tulare County sheriff confirms 6 people killed at Goshen home
When deputies arrived, they immediately noticed two victims and then a third in the doorway of the home.
Deputies found six victims total. All have been declared dead.
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Authorities believe there are at least two suspects at large, Boudreaux said. No arrests have been made.
"We believe that this was a targeted family," the sheriff said.
"This was very personal," Boudreaux said. "We also believe that it was a message being sent."
Authorities "believe there are gang associations involved in this scene, as well as potential narcotics investigations," Boudreaux said.
"It was like a cartel-style execution," the sheriff said.
One week ago the sheriff's office conducted narcotics search warrants at the house, he said.
ABC News contributed to this report.