NEW YORK (CNN) -- A rally Wednesday afternoon at Columbia University was held to protest the discovery of a noose on the office door of an African-American professor.

The noose was found Tuesday, hanging from a door at Columbia's Teachers College. more photos »

The noose was found Tuesday at Columbia's Teachers College, said Joe Levine, executive director for external affairs at Teachers College.

The New York Police Department is investigating the matter as a hate crime.

The apparent target, Madonna Constantine, 44, is a professor of psychology and education at Teachers College. She co-wrote the book "Addressing Racism: Facilitating Cultural Competence in Mental Health and Educational Settings."

Constantine issued a statement saying, "I am upset that the Teachers College community has been exposed to such an unbelievably vile incident, and I would like us to stay strong in the face of such a blatant act of racism.

"Hanging the noose on my office door reeks of cowardice and fear on many levels. I want the perpetrator to know that I will not be silenced."

The noose was discovered about 9:15 a.m. Tuesday by a colleague of Constantine. It appeared to have been placed on the door between 8 and 9:15 a.m., police said.

Security cameras monitor the entrance to the building, but there are none in the hallway where the noose was discovered, Levine added.

The building, which is open 24 hours a day, is accessible only to those with a Teachers College ID card or other credentials, he said.

No arrests have been made and no suspects have been identified, police said.

Reacting to the news, more than 150 undergraduates attended a meeting Tuesday night on campus, and more than 120 Teachers College students expressed outrage at a gathering in their dining hall as well, according to the student-run newspaper Columbia Spectator.

University President Lee Bollinger denounced the incident in a statement sent out to the Columbia University community: "Tolerance and mutual respect are among the core values of our diverse community, and all of us must confront acts of hate whenever they occur within it. As I said last night, an attack on the dignity of any member of our community is an assault on all of us."

Teachers College President Susan Fuhrman said that she and the community "deplore this hateful act."

Wednesday's protest started around 2 p.m. A town hall meeting for professors, students and staff was set for 3:30 p.m. It was closed to the public.

Columbia has had a spate of bias-related incidents in recent years, but Levine said, "I've never seen anything like this here."

Student Liz Tortu said students received a university e-mail describing the incident. "I was just stunned," she said. "I would never think something like that would happen here. I was just very surprised and saddened also."

The student paper reported the noose's discovery came on the heels of several recent politically and racially charged events at Columbia, including the controversial visit of Iranian President Mahmoud Ahmadinejad.

It also follows news reports of racial tensions in Jena, Louisiana, that attracted national attention. In the "Jena 6" case, white students in the small town hung nooses from a schoolyard tree after black students sat under it. Marchers last month protested how authorities handled the cases of six black teenagers accused of beating a white student at the same school, several weeks after the noose incident.

Constantine has been recognized for her work by the Society of Counseling Psychology and the Society of the Psychological Study of Ethnic Minority Issues, and she received an Outstanding Research Award from the American Counseling Association.

She is on the editorial boards of the Journal of Counseling Psychology, Journal of Multicultural Counseling and Development and Journal of Black Psychology.

Teachers College has more than 5,000 graduate students and 165 faculty members, according to school officials. E-mail to a friend

CNN's Allan Chernoff, Rob Frehse and Andrea Stout contributed to this report.

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