A former student at the US Central School for the Visual and Performing Arts (St. Louis) has opened fire, leaving 3 people killed, including the shooter, NBC News reported.

According to police, the 19-year-old entered the institution with a rifle in an aggressive, violent manner.

There was no mystery about what was going to happen, Interim City Police Department Chief Mike Sack said.

A graduate student shot and killed health teacher and a 16-year-old student. Nine people were injured in the shooting, eight of whom were transported to a medical facility with gunshot wounds. Some students had to jump out of the window to avoid the attack.

However, as Sack noted, the motives for the crime are unknown. According to his speculation, the young man may have suffered from a mental disorder.