The granite ramparts of the U.S. Military Academy, the nation's oldest military post, and the villages in its shadow have been jolted by charges that children were sexually and physically abused at the day-care center on the grounds.

Two military families literally broke ranks, hired an outside lawyer and filed suit Sept. 20 in federal court, saying they were outraged at insensitivity and inaction by West Point brass and the FBI as long as the parents remained "in regular channels" and did not make waves.

Because of its setting, in an intimate community with all the stratification of military tradition, the case throws into unusually high relief some of the social conflicts and ambiguities associated with a crime in which the victims -- and only witnesses -- are often babies, and the abusers are almost never strangers, but relatives or other familiar grown-ups.

Child sexual abuse is not a new crime. But until recently it remained in the shadows. Now, courts, law enforcement and social services authorities are scrambling to respond to an explosion in reported cases nationwide in the last few years, which some attribute in part to the increase in the number of women who work and leave their children with others.

The federal investigation under way at West Point comes after a period during which the Army wrestled with the reality of soaring numbers of women in its ranks, changing life styles and intensified pressure to concern itself with matters such as child care.

Since the two families went public, their lawyer says, there has been a marked increase in activity on the case.

Special investigators from the FBI's "pedophile unit" have moved into the Palisades Motel on the outskirts of Highland Falls, the tiny village that provides most of the work force for the academy, including the child-care center.

The U.S. attorney's office has become actively involved. And, according to a county child protective services official, reports of additional cases of abuse are pouring in to investigators.

"This is a very active investigation, getting the highest level of attention," said Dennison Young Jr., associate U.S. attorney for New York's Southern District. "We hope to conduct a very thorough investigation that will be fair, recognizing it's a very sensitive matter."

West Point officials, he added, are cooperating fully.

No arrests have been made. The child-care center, an old brick complex near the academy athletic field with a view of the Hudson River's sweep through the Highlands, continues to operate. It has a staff of about 40 and is attended by approximately 130 children of post military and civilian personnel. Operated by the military, it bears a gray academy shield inscribed "Building 673."

Two young female teachers, "locals" named by children as the abusers, no longer work there. Identified as "X" and "Y" in court documents, they were removed from duty with pay after the initial allegations surfaced in late July and mid-August. Earlier this month, one was assigned an administrative position in the directorate that oversees the center, according to a West Point spokesman; the other has chosen to leave the post work force.

Some parents of children involved say they have been stunned twice -- once when they learned of the abuses, and again by the reaction of their community when they pressed for redress. In essence, they say, people have taken sides on the issue, with some viewing them as "traitors to the Army" for marring the academy's "Duty, Honor, Country" image by going public.

"I can't understand it," said one mother. "There shouldn't be sides on this."

Some of those familiar with the investigation -- townspeople and others -- though they will not let their names be used, caution that emotions are raw and people should avoid jumping to conclusions.

"This is an educational process for investigative agencies as well as parents and everybody else involved," said Dan Bloomer, an official of the Orange County Department of Social Services, which works with a family advocacy council on the post. Bloomer said he does not believe charges that West Point officials tried to sweep the affair under the rug.

The Times Herald-Record, based in nearby Middletown, described the predominant reaction in the community to the lawsuit as "shock," even though Lt. Gen. Willard W. Scott Jr., superintendent of the academy, mentioned the allegations in his annual briefing to the staff and faculty on Aug. 17. The paper quoted one woman as speculating that many husbands never told their wives what Scott had said.

Some people express concern for the accused day-care workers, whose guilt has not been proven legally and for workers still at the center who are now afraid to touch a child.

West Point officials will say little about the matter. In the Sept. 28 Pointer View, the academy newspaper, an article took note of the lawsuit, expressed official concern and reassured parents that the child-care program was safe.

Last week, the four parents who filed suit sat in a toy-cluttered living room, not far from where uniformed cadets were drilling on the academy's parade grounds, and spoke bitterly about the scandal that "couldn't happen here."

Their names are a matter of public record in court filings, and most people in their community know who they are; The Washington Post has agreed to withold their names to protect the children.

One of the fathers is an Army internist with the rank of captain. The other father is a veteran enlisted man, a sergeant-major; his wife spent nine years as a combat medic.

Their two daughters, alleged victims in the case, romped nearby. The 2-year-old clutched the same Cabbage Patch doll she had clung to during an interview in which her "testimony" was videotaped for court use. On the tape, the girl, squirming and wanting to play something else, had pushed aside an anatomical doll purchased for the purpose and instead grabbed her own doll to show a persistent social worker, matter-of-factly, what her teacher had done to her.

The families' ordeal began July 27 when the enlisted man and his wife rushed their 3-year-old daughter to the post hospital to be treated for vaginal bleeding, after she began screaming when she tried to urinate. According to hospital records, the child told an emergency-room doctor that her "teacher did it." Later, in one of the videotaped interviews, she indicated that the teacher had inserted a pen into her.

The mother later spoke of having to "grip the stirrups to force myself to look at those . . . marks."

The second couple -- the captain and his wife -- questioned their daughter after hearing about the first case. The child indicated that another teacher had fondled her.

The cases were referred to the FBI, which has jurisdiction in cases involving civilians on a federal reservation.

The families' lawyer, William E. Crain of nearby Newburgh, asserts in court documents that the FBI "essentially 'closed' the investigation when the two teachers. . . 'passed' polygraphs." He claims further that "the acts could only have been performed by a severely deranged and mentally ill individual" who thought her actions were right, in which case the polygraph results could be invalid.

Initially, an FBI agent, identified only as "Z," accused the first child of lying and spread the "outrageous innuendo" that her parents had abused her, the court documents charge.

In the second case, word suddenly spread around the post that it was "only a diaper-changing incident," the captain said.

When the family sought support from their church, their chaplains delivered a supportive general sermon to the congregation, the captain said. But he said one chaplain chastised them privately, saying, "Don't you know such a thing could never happen at West Point?" and suggested, "Let's talk about your anger."

Crain says that, so far, 11 families have come to him with credible evidence of sexual or physical child abuse at the day-care center. He is calling for a grand jury.

He agreed to cooperate with federal authorities in their investigation only after they agreed not to share the information with West Point officials, he said. "Many who contacted me were reluctant to come forward for fear of harm to their careers and causing displeasure at West Point," Crain said.

Thus far, the captain's is the only officer's family to come forward, according to Crain; the rest are enlisted personnel or civilians.

The civil suit seeks screening of all children at the center to check for other instances of abuse, permanent transfer of the accused staff members, and admission of responsibility and compensation by West Point.