(JTA) — The FBI is investigating a series of mass emails sent to students at the University of Michigan threatening violence against Jews and blacks.

Three emails were sent Tuesday night to students in the university’s computer science and engineering program, according to news reports.

One of the emails, with the subject line “Jewish Student Diversity,” read: “Hi you f***ing filthy jews, I just wanted to say the SS will rise again and kill all of your filthy souls. Die in a pit of eternal fire! Sincerely, Dr. Alex Halderman.”

J. Alex Halderman, a professor at the university, denied sending the emails and told the campus newspaper that it takes little sophistication to make it seem like the emails were sent by him. A statement from the university on Wednesday confirmed that the emails had been forged.

The other two emails, written under the subject line “African American Student Diversity,” threatened to kill black students and saluted the KKK and Donald Trump.

University of Michigan President Mark Schlissel condemned the emails in a tweet early Wednesday morning.

In a statement Wednesday, the university said campus police had increased patrols near the engineering school and that a joint criminal investigation had been launched with the FBI.