An anonymous letter threatened to behead schoolchildren in Rhode Island, forcing police departments in the state to dramatically increase security measures at grade schools Wednesday.

A letter sent to school districts in Warwick, Cranston and Johnson declared that “beheading is planned,” the Providence Journal reported. The FBI is reportedly assisting the police in security measures after a meeting Wednesday morning.

“While the words are very chilling, I certainly would want to emphasize that the safest place right now is in school,” said Warwick Police Chief Stephen McCartney in a statement. “I’ve got a police officer in every school and so do the other jurisdictions. We are providing the security that is necessary. We know that whoever did this decided to create the most chaos he could by picking on the most vulnerable.”

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