Police received reports of shots heard at the Lowell Elementary School campus, located at 625 S. Seventh St., at 9:25 p.m., according to police.
When officers arrived at the school they found the 18-year-old suffering from at least one gunshot wound.
He was pronounced dead at the scene by paramedics, police said. No suspects are in custody, police said.
The circumstances and motive of the shooting are under investigation. Police are also investigating if the shooting was gang related.
This incident marks the city's 12th homicide of the year.