South Burlington police have given the all-clear after converging on the Rice Memorial High School campus Wednesday in response to a call of an ‘active threat.”

Meanwhile, Vermont State Police said law enforcement across Vermont and the U.S. have received calls that report threats of violence at schools. None of the threats have been deemed credible and appear to be part of a nationwide campaign.

“During our investigation it was found that multiple law enforcement agencies across the state are receiving calls reporting shooting events at local schools. Currently these incidents appear to be all hoax phone calls,” the agency said in an email.

According to state police, the calls likely originate from Voice over Internet Protocol, or VOIP, phone numbers or fake 802 numbers and “appear to be associated with ongoing nationwide hoax phone threats of school shootings, bomb threats, and other violent events that have proved to be unfounded.”

The Essex Police Department said it received a call just after 9:50 a.m. reporting an active shooter at an Essex school. The department, after checking in with the local schools, said there were no threats.

Montpelier City Manager William Fraser said a threat to Montpelier High School came from an out-of-state number. Emergency personnel swept the school twice and found nothing.

“This was clearly a hoax call,” Fraser said.

South Burlington Police Chief Shawn Burke said the incident at Rice Memorial could be what’s known as ‘swatting,” which is when someone makes a prank call in an attempt to draw large numbers of police officers to a scene.

“We understand that these reports are wide spread in Vermont,” he said.

Vermont State Police said the investigation into the hoax threats is continuing and more information will be released as it becomes available.