CBS News reports that sources close to the investigation said authorities found evidence that Henderson and Rupnow were following each other’s social media accounts. However, there isn’t any evidence that the two suspects were in direct contact or communication with each other.

A month after a student opened fire at Abundant Life Christian School, another killed a classmate at Antioch High School. Both were active in an internet subculture that glorifies mass shooters and encourages young people to commit attacks.

A female student was killed and another student was injured Wednesday in a shooting in a Nashville high school cafeteria, authorities said, jarring the community nearly two years after another school massacre sparked a debate for gun reform in Tennessee.

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.