A 16-year-old Ballou Senior High School student was accosted at knife point yesterday morning in Southeast Washington as she walked to school, but was freed by her assailant after a brief tussle, D.C. police reported.

The attack, the sixth involving girls from D.C. schools since the start of school this year, occurred in a wooded area in the 3600 block of 6th Street SE, police said. The Ballou student told police that a man in his early thirties approached her from the rear, grabbed her by the arm, put a large knife to her neck and tried to pull up her skirt.

The girl yelled, "Stop, stop!" at her attacker, according to police, and offered him money. The assailant then released the girl, told her to get out of the woods and not to tell anyone about the attack, police said. The girl was not injured.

The assault came as D.C. police continued their investigation of the stabbing death of Latanya Lassiter, a 13-year-old Northeast Washington girl who was assaulted as she walked alongside Woodson Junior High School at 10 a.m. Saturday.

D.C. police Lt. John Harlow said detectives are "interviewing everyone who saw anything" near the school at the time of the attack on Lassiter and are trying to compile a composite sketch of the assailant. The girl lived for more than 12 hours after she was stabbed in the chest and told her mother that her assailant was a man she had never seen before.

In other recent incidents, a 10-year-old girl on an errand for her aunt was abducted and raped near a Southeast Washington school, while three 5-year-old girls, all pupils at Bancroft Elementary School in Northwest, were sexually assaulted or kidnaped.

A suspect was arrested in the rape case, while police are continuing their investigations in the other incidents.

Capt. John Collins, commander of the police department's sex offense branch, said the three Bancroft attacks "do have some similarities," but that the other assaults do not appear to be related.

While no statistics were immediately available, school security chief Edgar Dews said, "It is not normal to have this number of sexual assault cases reported in such a short period of time."

The attacks have angered many parents at the schools involved and prompted questions about the quality of security on school grounds.

D.C. Schools Superintendent Floretta McKenzie sent a letter yesterday to all 150 principals in the city ordering them to give pupils specific safety instructions, such as warnings to avoid secluded or isolated areas and asking that students report any unknown persons in schools to teachers or staff members.

In addition, McKenzie said officials are reviewing the school system's curriculum to determine if classes ought to be added to make students aware of child and sexual abuse. Some, but not all D.C. schools now have courses that include instruction on such offenses.

"We realize this is a total community problem," McKenzie said. "We are trying to look at the idea of a comprehensive way that city agencies can address the issue of child abuse and school safety."

D.C. School Board president David H. Eaton said school officials and police will impose new security measures at city schools starting tomorrow. Without giving details, he said the new security would be "comprehensive . . . the result of many hours of working with community leaders, parent-teacher association representatives, D.C. recreation officials, as well as police."

"Safety in this city for our children is something everyone in the community has to become involved in," Eaton said.