SANTA ANA, CALIF. — Homeless people in Orange County were put on alert by police and advocates concerned that they’re the target of a serial killer who has slain three homeless men.

Police said an attacker has stabbed three homeless people to death in north Orange County.

As a precaution, the Orange County Rescue Mission handed out flashlights and whistles to the homeless on Thursday, in an effort to help them protect themselves, said Jim Palmer, the group’s president.

Palmer’s group is encouraging area homeless to sleep in groups, or better yet, come inside to a shelter.

“Our goal is to get them into those beds and fill those beds,” he said.

Darryl Bossier, 49, said he sleeps outside the Orange County administration building in downtown Santa Ana — one of a dozen transients who use the benches that zigzag across the courtyard as a place to rest each night.

“I’m a watchdog. I don’t want them to get anybody,” Bossier said of the killer, adding he sleeps only about four hours a night. “Who wants to wake up next to somebody dead?”

He said he learned of the killings three days ago but would not go to a shelter because he had his cellphone stolen from his bag the last time he slept there.