What happened to just handing out a couple detentions? Luckily, school was not in session Wednesday night when a National Guard F-16 fired on Little Egg Harbor Intermediate School, in the vicinity of (globally speaking) Atlantic City, with 25 rounds from a wing-mounted cannon. The F-16, flying at 7,000 feet, was headed for a target on a practice range 3 1/2 miles away. A custodian in the building was unhurt, but at least eight of the three-inch-long bullets penetrated classrooms. Operations at the firing range have been halted while the incident is investigated. Previously, wayward bombs have ignited forest fires near the range, but this is the first time a building was hit. The jet is based at Andrews Air Force Base in Maryland and belongs to the 113th Wing of the District of Columbia National Guard. The gunnery range is used for about 3,700 sorties a year by fighter jets and helicopters. When the practice range first opened after World War II, there were 5,000 residents in Little Egg Harbor. Now there are 25,000, the Newark Star-Ledger reported yesterday, along with more developments and more congestion. The 2,400-acre range site is deep within the Pine Barrens, a million-acre stretch of undeveloped coastal land.