The Los Angeles Police Department's command staff was meeting to determine if a threat continued, she said.
"That's of course something we are thinking about and looking into because it's three within the span of an hour," she said.
In the first attack, someone fired gunshots at five people riding in a car to attend church at 5:50 a.m. in San Fernando, police said. A 20-year-old woman was found dead at the scene. Two others were injured; one of them was taken to the hospital in critical condition.
Forty-five minutes later, at 6:35 a.m., police responded to a call of shots fired in Sylmar and found a man in his mid-20s to mid-30s dead at the scene.
Ten minutes later, a third woman was found dead of a gunshot wound to the head, Preciado said.
No further details were released. Police planned to hold a news conference Sunday afternoon to discuss the investigation.
The shootings took place in the San Fernando Valley, about 30 miles north of downtown Los Angeles.
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