A teenager who opened fire with a 9 mm pistol in his Nashville high school cafeteria fired a total of 10 shots within 17 seconds of entering the room, according to police.

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.

Police say a shooting at a Nashville high school has left one student dead and another woulded. Metro Nashville Police spokesperson Don Aaron said during a news conference that the 17-year-old gunman later shot and killed himself with a handgun.