MONROE — At least five law enforcement agencies are investigating a telephoned bomb threat to Sandy Hook Elementary School at 375 Fan Hill Road, which was received on the morning of Wednesday, October 1.

The incident amounts to “a terroristic act” heavily punishable by federal criminal law, according to a spokesman for Monroe Police Department.

Monroe Police Lieutenant Brian McCauley said October 2 that Monroe police are being aided by Newtown police, state police, the Federal Bureau of Investigation (FBI), and the US Attorney’s Office for Connecticut in the probe into the threat received at the school at about 9:39 am on October 1.

Lt McCauley declined to disclose the specifics of the threatening call because the case is under investigation.

Monroe police detectives are “very positive” in terms of the probe producing an arrest, he said.

“We are working with the FBI,” and seeking to learn the identity of the caller, Lt McCauley said.

After the bomb threat was received, Sandy Hook School students and staff evacuated the building and stayed at the adjacent Jockey Hollow Middle School. Students remained there until they could be picked up by their parents or transported home by school bus, the lieutenant said. Busses departed from the school grounds at noon.

There were about 475 people inside Sandy Hook School, including students and staff, when the threat was received. There were no injuries.

Sandy Hook School students have attended class in what had been a vacant Monroe school building, formerly known as Chalk Hill Middle School, since January 2013.

Following 12/14, when 20 first graders and six educators were were killed by a rampaging gunman, the former Sandy Hook School building on Dickinson Drive closed. That school was later demolished. A new Sandy Hook School planned for that site is expected to open for the 2016-17 school year.

Lt McCauley said that after Sandy Hook School parents received notification of the October 1 incident, there was a steady stream of parents traveling to the school to transport their children home.

Of the students’ response to the emergency, Lt McCauley said the children remained in very good emotional condition. School staff members kept the children calm, Lt McCauley said.

School officials did not initially inform the students about the nature of the emergency that required their evacuation.

Following a thorough search of the Sandy Hook School and grounds, no suspicious objects were found, the lieutenant said. Police concluded their search in the afternoon, he said.

Each bomb threat is a unique bomb threat, he said.

“This [incident] will be considered a terroristic act … This is taken very seriously,” Lt McCauley said.

The incident involved a threat of harm through a weapon of mass destruction, he noted.

“This [crime] carries significant federal penalties,” he added.

Asked for comment on the incident, Newtown Police Chief Michael Kehoe said, “We support and assist as needed the Monroe police.”

“We thank the Monroe police for their swift response and professional services they give to Sandy Hook Elementary [School] staff and students,” Chief Kehoe said.