MACON, Ga. - The FBI's Atlanta field office says that it is joining an investigation into a rash of hoax active shooter calls targeting colleges across the country.

Authorities say schools in Macon have had to go on lockdown three times this week due to fake threats.

MORE: University of South Carolina issues all clear after unconfirmed active shooter report

What we know:

On Monday alone, law enforcement responded to calls claiming active shooters at Arkansas, Northern Arizona University, Iowa State, Kansas State, the University of Colorado-Boulder and the University of New Hampshire. More calls were made Tuesday at the University of Kentucky and West Virginia University.

In Georgia, Central Georgia Technical College and Rutland High School were advised to shelter in place followi

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