EDISON - At least eight New Jersey schools and a hospital were placed on lockdown Monday, all apparently victimized by "swatting" incidents.

Schools in Princeton, Cresskill and West Milford all received hoax calls that prompted them to go into lockdown mode, according to police.

A call was also made to Robert Wood Johnson Hospital in New Brunswick. It is unknown if all the calls are connected.

Earlier, a South Brunswick school was placed into lockdown after two district employees entered the school without checking in with the main office.

A Newark school was also placed into lockdown after a 14-year-old brought a gun into the school.

The "swatting" calls come in the wake of a series of similar hoaxes in New Jersey over the last few weeks.

Police departments across New Jersey, along with the FBI are investigating these hoax calls.