All public schools in Nashua, New Hampshire, will be closed Monday after authorities received a threat of violence against two schools in the district. The threat reportedly targeted students and staff at Nashua High School North and Nashua High School South.

The threat was received via email Sunday by a school administrator who later contacted police, a Nashua Police Department lieutenant said, according to the Associated Press (AP). An investigation was underway and the police department, school administration, and state and federal agencies were working to determine the credibility of the threat.

"Because the threat is specific and extends to several schools," School District Superintendent Mark Conrad reportedly said. "We will be cautious and close all of our public schools in Nashua tomorrow, Monday, Dec. 21."

Conrad told the Boston Herald that it was a “difficult decision” to close all 17 schools.

Lieutenant Kerry Baxter said that the schools in the district, which has nearly 12,000 students, will have extra patrols Monday, AP reported.

"Specific direction towards the two specific Nashua high schools. With a specific threats of violence is why we are kind of taking it seriously," Baxter reportedly said.