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 investigation into why a Nashville high school student fatally shot a classmate before killing himself has centered on his online writings, which authorities describe as concerning warning signs.

Police said the suspect fatally shot himself after killing a 16-year-old and wounding a 17-year-old at Antioch High School.