The Jacksonville Sheriff's Office provided limited details about the shooting, which occurred around 4 pm local time, but said two girls, aged 14 and 15, were struck and authorities were searching for two male suspects.
The office said the girls were taken to area hospitals with non-life threatening injuries.
"When I got word of the shooting there was a deep anger that permeated my whole being," said Duval County Public Schools Superintendent Nikolai Vitti.
"A level of frustration, being horrified and just sickened by the fact that our children can't be children, that students can't be students," he told the Florida Times-Union newspaper.
He said violence was "rampant" in the area, Reuters reported.