A National Guard F-16 fighter (search) jet on a nighttime training mission strafed an elementary school with 25 rounds of ammunition, authorities said Thursday. No one was injured.

The military is investigating the incident that damaged Little Egg Harbor Intermediate School (search) in southern New Jersey shortly after 11 p.m. Wednesday. The school is a few miles from a military firing range.

Police were called when a custodian who was the only person in the school heard what sounded like someone running across the roof.

Police Chief Mark Siino said officers noticed punctures in the roof. Ceiling tiles had fallen into classrooms, and there were scratch marks in the asphalt outside.

The pilot of the single-seat jet was supposed to fire at a ground target on the firing range three and half miles from the school, said Col. Brian Webster, commander of the 177th Fighter Wing of the New Jersey Air National Guard (search), which is responsible for the range. He did not know what led to the school getting shot up.

The plane was 7,000 feet in the air when the shots were fired. The gun, an M61-A1 Vulcan cannon (search), is located in the plane's left wing. It fires 2-inch-long bullets that are made of lead and do not explode, said Webster.

"The National Guard takes this situation very seriously," said Lt. Col. Roberta Niedt, a spokeswoman for the state Department of Military and Veterans Affairs. "The safety of our people and the surrounding communities are our foremost concern."

The jet that fired the rounds was assigned to the 113th Wing of the District of Columbia Air National Guard, based at Andrews Air Force Base in Maryland. The plane returned there after firing the shots, Webster said.

He would not identify the pilot or detail possible disciplinary measures.

Mike Dupuis, president of the township's Board of Education, said school workers are mindful that the firing range is nearby.

"Being so close to the range, that's always in the back of our minds. It is very scary. I have children in that school and relatives that work there," he said.

Schools in New Jersey were closed Thursday because of a teachers convention.

The 2,400-acre Warren Grove range, about 30 miles north of Atlantic City, has been used by the military since the end of World War II, long before the surrounding area was developed.

In 2002, an Air National Guard F-16 that had been practicing attacks at the range crashed along the Garden State Parkway. The plane's pilot ejected safely, and no one on the ground was hurt.

Errant practice bombs were blamed for forest fires that burned more than 11,000 acres of the Pine Barrens near the range in 1999 and more than 1,600 acres in 2002.