More threats were made to historically Black colleges on Tuesday, the first day of Black History Month, just a day after similar reports forced the closures of about half-a-dozen universities across the country.

Several colleges were similarly forced to shut down campuses early Tuesday morning. Those schools included Xavier University in New Orleans, Howard University in Washington, D.C., Morgan State University in Baltimore, Kentucky State University, and Jackson State University in Jackson, Mississippi.

“A bomb threat against the university is being investigated," said an alert from Howard University, which went out around 3:30 a.m.. "All persons on campus are advised to shelter in place until more information is available."

On Monday, at least six HBCUs were forced into lockdown by similar threats, including Southern University in Baton Rouge. Those campuses reopened Tuesday after authorities determined there was no danger to students and faculty.

Those threats are being looked into by federal investigators.