NEW ORLEANS — New Orleans police say they are investigating a gunfire incident outside a charter school.

Police said one 14-year-old was treated for a minor elbow abrasion at a hospital Monday afternoon and that the wound wasn’t believed to be from gunfire.

Police Chief Michael Harrison told reporters shots were believed to have been fired from a dark pickup truck outside the NET Charter High School. The campus was locked down immediately afterward but students were later released.

The injured student was among a group outside the building at lunch time. Harrison says investigators found another student in that group had gunpowder residue on his hands. Another student — not part of that group — was found possessing live ammunition, according to authorities. Their role, if any, in the shooting, was unclear.