Fairfax County investigators have found at least a dozen more bullets that they believe came from a police shooting range at Lorton where gunfire last week riddled a nearby neighborhood with stray slugs.

Police said yesterday that more than a dozen slugs have been recovered in addition to the 15 bullets initially reported to have struck a dozen town houses and three cars in the Newington Commons community. Some of the shells were found strewn on the decks of homes and in parking areas. One bullet tore through the window of a Honda Accord parked at a shopping center. The driver returned to find a bullet on the passenger seat.

The latest discoveries alarmed nearby residents, who said the training at the weapons facility on the grounds of the Lorton Correctional Complex appears to have been far more extensive than officials previously indicated.

Fairfax police now believe that more than 240 rounds were fired during the May 24 training drill, in which a D.C. police sergeant was supervising eight officers from the Fairfax County police, the U.S. Capitol Police, Defense Protective Services and Andrews Air Force Base Security.

D.C. police officials said previously that the officers were armed with MP5 submachine guns and were practicing a "fallen officer" exercise--lying on their backs and firing 9mm ammunition into the air--when they accidentally launched 12 to 15 rounds into Newington Commons.

"It's unbelievable," said Donna Conklin, whose home was hit by a bullet that lodged near the window of a bedroom in which a 3-year-old child was sleeping. "It's a miracle no one got hurt. We can't let this happen again."

D.C. Police Chief Charles H. Ramsey, whose department owns the firing range on the 3,200-acre Lorton grounds, will meet with area residents there tonight to address their concerns. Ramsey closed the firing range earlier pending an investigation, and yesterday his spokesman tried to blunt neighbors' worries. "The range is not going to open until [Ramsey] has reviewed everything and considered all options to improve the safety of the facility," said Sgt. Joe Gentile, a D.C. police spokesman.

But for some Newington Commons residents, they've heard it before--16 years ago, in fact, when the nearby Newington Forest community was pelted with bullets coming from Lorton. Several homes were struck by the .45-caliber shells, an event that led Fairfax to sue in an attempt to close down the firing range.

U.S. District Judge Albert C. Bryan Jr. ordered a temporary shutdown, and the District subsequently agreed to move the range from the eastern end of Lorton to the western side, which was then less heavily developed.

District officials also promised to add a number of safety measures, including berms to stop stray bullets.

Neal McBride, a resident of Newington Forest, which pushed for the range to close in 1983, said homeowners are more resolved than ever to shut down the facility. "We can't allow the District to schmooze us all over again. They said it wouldn't happen again. Well, it did. I say enough is enough."

The Lorton complex is scheduled to be closed, and its inmates moved elsewhere, by the end of 2001. Under the plan, the firing range also will shut down. But some area residents would like to see that happen earlier and will pressure Ramsey not to reopen the weapons facility.

In another development yesterday, Mike Lomonaco, commander of the Fairfax police criminal investigations unit, said a single .308-caliber slug that shattered a bedroom window last week likely came from the Lorton range as well.

The lone .308 slug amid all the 9mm ammunition had puzzled investigators because D.C. police had said it was unlikely to have been used in any weapons drill.

But Lomonaco said yesterday that, using infrared technology to trace the bullet's flight path, investigators now believe it came from the firing range and are investigating whether other officers were training with .308 rounds, which are used by police sharpshooters and can travel up to three miles.

CAPTION: At a recent news conference, D.C. Police Chief Charles H. Ramsey discusses errant gunshots at Lorton. At left is Fairfax County Police Chief J. Thomas Manger.