FORT LAUDERDALE, Fla.—A former neighbor of Nikolas Cruz said she called 911 two years ago because the teen said, in a social-media post, that he looked forward to buying a gun when he turned 18 so he could shoot up his school.

“I was pleading with the police [officer]. I said, ‘Please, is there anything you can do?’” Joelle Guarino said Saturday. “He said basically no, when you’re 18 you have a right to bear arms, and there was pretty much nothing he could do.”

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