NEW YORK - A National Guard F-16 fighter plane mistakenly fired off 25 rounds of ammunition at the Little Egg Harbour Intermediate School in South New Jersey on Wednesday night.

The pilot was meant to fire the rounds some 4.82km away at a military target range, Lt Col Roberta Niedt of the New Jersey Department of Military and Veterans Affairs told reporters in the Jersey shore township's police headquarters.

No one was injured as school was out and a lone custodian was inside the building when the bullets hit.

Damage was minimal as the non-exploding, 20mm bullets left only puncture marks in the school's roof and the asphalt outside the building.

The fighter jet was part of the 113th Wing, District of Columbia Air National Guard assigned to Andrews Air Force Base in Maryland.

An investigation is being conducted into how the pilot mistook the school, located on Frog Pond Road, for a target range.

- REUTERS