A veteran Montgomery County principal has been forced to retire after a school system investigation into complaints that he had sexually harassed several teachers and other school employees, according to school sources.

Darius E. Brown, the principal of Twinbrook Elementary School in Rockville, submitted a brief, handwritten retirement letter Monday and was asked to turn in his school keys on the spot, school officials said yesterday.

Montgomery school spokesman Brian Porter confirmed that Brown had been under investigation since June 12, when Twinbrook employees lodged "very serious" allegations against the principal. Porter would not confirm the nature of their complaints, but said that none of them involved children.

The school system's personnel director, James L. Shinn, who handled the internal investigation, refused to comment on it.

But sources said that six women school employees, most of them teachers, told school investigators that Brown had harassed them sexually during the last few years.

In one case, a teacher complained that the principal had kissed and hugged her repeatedly against her will, according to a source. Other sources said the complaints included both verbal and physical harassment since shortly after Brown arrived at Twinbrook as principal four years ago.

"Some were one-time incidents. Others were repeated," a source said. Another source said that school officials were prepared to begin moving immediately to oust the principal if he had not relinquished his job.

"The matter is certainly serious enough. No time would have been wasted," the source said.

Brown, 55, has worked in the Montgomery schools since 1962. He was a teacher and assistant principal for 15 years before becoming the principal of Sligo Middle School and, later, Richard Montgomery High School. In 1986, he became principal of Twinbrook, which enrolls about 600 children in kindergarten through fifth grade.

He has a master's degree in education from Bowie State University and received an annual salary of $82,287. School officials said that he is eligible for early retirement, although they could not say what his retirement payments would be.

Reached yesterday, Brown's wife said that he was not home and would not be available to comment. Several teachers reached Monday and yesterday declined to discuss their principal's abrupt departure.

Twinbrook's assistant principal, John Isacson, said that Brown had told him he had decided to retire early to devote more time to a doctoral dissertation. "He said school gets in the way of things he wants to do. Basically, that's it," Isacson said. But he added, "There is a lot of rumor, gossip, innuendo."

According to Porter, Brown has been placed on leave with pay until Sept. 1, when his retirement takes effect. Porter said the school system plans by Friday to name an interim principal, probably a recently retired administrator who would open the school and remain through September or October.