At least six historically black colleges and universities received bomb threats Monday morning, disrupting campus operations and launching police investigations.

Southern University and A&M, Howard University, Bethune-Cookman University, Albany State University, Bowie State University and Delaware State University all received bomb threats this morning, according to campus spokespeople or social media posts.CNN has reached out to the FBI for comment.

Five schools continue to investigate the threat and remain either on lockdown or have issued shelter in place orders.