-- Nashua, New Hampshire, officials ordered public schools in the city to be closed Monday after receiving a "detailed threat of violence."
Nashua School District Superintendent Mark Conrad said the district was working with police to determine the credibility of the threat.
"We have received a detailed threat of violence to harm students and staff at both high schools," Conrad said in an announcement on the district website.
"The threat is specific to tomorrow (Monday)," he said. "Because the threat is specific and extends to several schools, we will be cautious and close all of our public schools in Nashua tomorrow, Monday, December 21st. I do expect our schools to reopen on Tuesday. I regret any difficulties this creates for working parents but safety must remain our first priority. Thank you."
The district includes 12 elementary schools, three middle schools and two high schools.
New Hampshire Gov. Maggie Hassan said the State Police and state emergency management officials were working with the Nashua Police Department, local public safety officials and the FBI to determine whether the threat is credible.
"We will continue to monitor the situation and work together at the state, local and federal levels to investigate the threat and keep our communities safe," Hassan said.
The threat of violence is the third against a school district in the past week.
Los Angeles officials ordered its public schools closed last Tuesday, after officials there said they had received an emailed threat mentioning violence against students, including attacks, assault rifles and an implication of explosive devices, police said.