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.

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.

The two were among six other people wounded in the shooting, in which a student opened fire in a study hall, killing two people before committing suicide.

Law enforcement officials seeking a motive for a shooting at Nashville’s Antioch High School on Wednesday morning are examining alarming social media posts and writings tied to a teenager police say shot and killed a 16-year-old girl.

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.