One of the 12-year-olds threatened to shoot four of his classmates, the other posted a threat on Instagram and an 11th grader threatened “Antioch part two,” according to police.

It is clear that Henderson was significantly influenced by web-based material, especially that found on non-traditional sites that most would find harmful and objectionable.” ...

The shooter was “significantly influenced by web-based material, especially that found on non-traditional sites that most would find harmful and objectionable,” police said.