Transcript for Razor Blades Found Near San Diego Playground
terrifying safety alert for parents. It's a growing problem nationwide. Razor blades found planted in the park. Two boys slashed by razors hidden in the grass. Reporter: Barefoot in the park. Not a good idea near this California playground. They stepped on razor blades. Reporter: Cassie's two sons were injured Wednesday, in San Diego's bonita cove park, by razor blades someone had planted near the playground. Paramedics were able to pull the razor blades out. Reporter: Police searching with metal detects found 19 razor blades had been hidden nearby. This is the fourth time in a year someone has planted razor blades in this park. And there's been a rash of similar crimes across the country. Whatever sick and perverted thing you can think of, once it becomes viral, other people will pick up on it and end up copying you. Reporter: A month ago, in east Moline, Illinois, 3-year-old madden was climbing the monkey bars. He said ouch. And then, he said, bleeding. Reporter: His parents found blazer blades taped to the bars, the swings and the climbing wall. Razor blades were everywhere. Reporter: In Philadelphia, more razor blades found in this playground. Luckily, no one was injured. Someone would do that to this nice park. Reporter: The razor blade cases appear to be unrelated. And authorities won't say if they're close to catching the culprits. Spoiling innocent springtime fun with hidden hazards. For "Good morning America," David Wright, ABC news, los Angeles.
This transcript has been automatically generated and may not be 100% accurate.