The Federal Bureau of Investigation says the investigation into the bomb threats against Historically Black Colleges and Universities is being investigated as hate crimes.
In a news release, the agency said the investigation into the bomb threats "is of the highest priority," and more than 20 field offices across the U.S. are involved in the investigation, which the FBI Joint Terrorism Task Forces are leading.
"These threats are being investigated as racially or ethnically motivated violent extremism and hate crimes," the agency said.
The FBI said no explosive devices had been found at any location.
Several colleges, including Kentucky State University and Xavier University of Louisiana, were placed on lockdown after receiving bomb threats on Monday and some on Tuesday, which was the first day of Black History Month.
Howard University received threats on both days.
The statement also added they are also investigating threats made against houses of worship.