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.

A 17-year-old boy armed with a pistol, identified by authorities as Solomon Henderson, fired several shots in the cafeteria. A female student, 16-year-old Josselin Corea Escalante, was killed and a boy was grazed on his arm. Henderson then shot himself in the head and was fatally wounded.