An AI gun detection system installed in a Nashville, Tennessee high school couldn’t spot the gun a 17-year-old used to fatally shoot another student and himself earlier this week, according to district officials.

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.

A student opened fire inside Antioch High School, shooting two other students and then himself, the authorities said. A female student and the shooter were killed, officials said.