A group of students at a Washington high school for the deaf scrawled "KKK" and swastikas on a black student's body with a marker while holding him against his will, police said Wednesday.

District of Columbia police are investigating the Saturday night attack as a possible hate crime, Chief Cathy Lanier said. The incident began in the dorms of the Model Secondary School for the Deaf, on the campus of Gallaudet University.

Seven students — six white and one black — took part in holding the black student, Lanier said.

University officials would not say whether they had been disciplined, but in a campuswide e-mail Wednesday, Katherine Jankowski, dean of the center that includes the high school, said the seven were sent home.

The school discussed the incident at an assembly Monday and has worked with students on issues of diversity and race, said Stephen Weiner, provost of Gallaudet.

"We do not tolerate any kind of action, any kind of behavior of this type," Weiner said.

Lanier said the attack began when two groups of students, one white, one black, were "horsing around" in the dorms. The groups eventually separated, but the seven students took the black student and held him for about an hour.

The student who was held contacted Gallaudet authorities, who called police early Sunday. He is at home with his family, the provost said.

No charges have been filed, but police said they have identified all seven students involved; they range in age from 15 to 19. "We take it very seriously," Lanier said.

Gallaudet, the nation's only liberal arts university for deaf students, was founded in 1864 by an act of Congress. The university had about 1,800 students last year.

About 170 students attend the Model Secondary School, with roughly 100 living in dorms on campus, Weiner said.

It is part of Gallaudet's Laurent Clerc National Deaf Education Center, which also includes an elementary school. The center works on developing courses and teaching methods for deaf and hard of hearing students.