A black professor discovered a hangman's noose on her office door at Teachers College at Columbia University, and police said they were investigating the case as a possible hate crime.
Teachers College President Susan H. Fuhrman sent an e-mail Tuesday to the college's 5,000 students and 150 faculty members explaining why police were on campus.
"The Teachers College community and I deplore this hateful act, which violates every Teachers College and societal norm," the statement said.
The school has not identified the 44-year-old professor but students said she teaches a class on racial justice.
"It's really really disturbing," student Mary Owens said. "These racist practices have been in place for so long, and they really have to be rooted out by everyone."
Student Mikayla Graham said the incident was shameful.
"You would think, Columbia being such a diverse campus and New York being such a diverse city, it shouldn't happen here," she said.
Nooses, reviled by many as symbols of lynchings in the Old South, have been in the news recently because of a case in Jena, Louisiana.
Last year, three white students hung nooses from a big oak tree outside Jena High School. They were suspended but not prosecuted. Racial tensions rose and a white student was beaten unconscious three months later.
Recently, thousands of people protested the arrests of six black students in the incident.