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SANTA CLARITA, Calif. — The blaring sirens came around midnight accompanied by the emphatic voices of police officers on loudspeakers ordering all residents to evacuate from their homes in the canyons north of Los Angeles.

Cindy and Frank Cruz were not sure there was an immediate threat, but they and many others did not hesitate to flee.

“People aren’t taking any chances,” said Ms. Cruz, who is seven months pregnant and who spent the night in the couple’s car in the parking lot of a Denny’s. They were among 50,000 people ordered to leave their homes.

The trauma of catastrophic fires over the past two years has scarred California, which has seen more than 1,300 wildfires ignite over the past two weeks alone.