Two counselors and two campers, ages 12 to 17, have been charged with sexually and physically abusing three boys at a Baptist overnight camp last month in Gainesville, Prince William County police said yesterday.

The accusers and suspects, all boys, were attending an overnight summer camp at the Northern Virginia Baptist Center, a 22-acre facility on Glenkirk Road, the week of July 18-23, police said.

The four suspects were charged with a total of 19 counts, including object sexual penetration, a felony. Three of the four suspects were charged with assault and battery, a misdemeanor. The accusers are 10, 11 and 12 years old.

"It's very unusual for a crime to be committed at a church camp, particularly crimes of this nature," said Commonwealth's Attorney Paul B. Ebert. "You'd think it would be a very safe environment and there would be more of a quality type of atmosphere."

The suspects are two 12-year-old campers, a 17-year-old counselor from Prince George's County and a 15-year-old counselor from Fairfax County.

"We make a lot of sexual assault arrests on caretakers or acquaintances," Maj. Ray Colgan said. "I don't know of anything like this since I've been involved in criminal investigations."

Police said they began investigating after one of the alleged victims told his parents.

"We just started talking to other kids at the camp, and they confirmed what went on," Colgan said. "It started out as horseplay."

Most of the abuse occurred at night in a camp dormitory of 13 boys, and it began when the counselors thought the campers were misbehaving, police said. Detective Dennis Mangan, a police spokesman, said the suspects held the campers' hands behind their backs and punched them.

A fourth boy, who is 7, tried telling adults what was going on during one of the incidents but was locked in the cabin.

"They were nighttime pranks," Mangan said. "Anytime [the alleged victims] would say something out of line, that's how [the suspects] would get back at them."

A man who identified himself over the telephone only as a minister "in charge" of the Northern Virginia Baptist Center declined to comment.

Mangan said that once the police investigation was launched, the center sent letters to parents telling them what had allegedly happened and canceled the second week of the camp.

The suspects, who turned themselves in after being called by police, are being held without bond at the county's juvenile detention center and are expected to be arraigned this week.