Six juveniles have reportedly been identified by the FBI as persons of interest in bomb threats against more than a dozen historically Black colleges and universities at the start of Black History Month.

The tech-savvy minors, in scattered locations across the country, used sophisticated ways to disguise the source of the online threats, NBC Washington first reported, citing an unidentified law enforcement official. The Washington Post and The New York Times also reported the FBI had identified persons of interest.

The FBI, in a statement to HuffPost on Wednesday, said the investigation into the threats is of the highest priority for the Bureau and involves more than 20 FBI field offices across the country. The threats are being investigated as racially or ethnically motivated extremism and as hate crimes, the FBI said.