Officials in Nashua, New Hampshire, told all public school students Sunday to stay home Monday because of a "specific" threat aimed at two high schools.

"We have received a detailed threat of violence to harm students and staff at both high schools," Superintendent Mark Conrad announced on the school district's website Sunday. "The threat is specific to tomorrow [Monday]. We have been working closely with the Nashua Police Department, which is still working at this time to determine the credibility of the threat."

Because "the threat is specific and extends to several schools," Conrad added, "we will be cautious and close all of our public schools in Nashua tomorrow."

He said he expected them to reopen Tuesday.

In a statement Sunday, Governor Maggie Hassan said that officials "are closely monitoring the situation in Nashua" and that "State Police and state emergency management officials are working closely with the Nashua Police Department, local public safety officials and the FBI."

The threats come less than a week after Los Angeles officials responded to threatening emails by shutting down their entire public school system — more than 1,500 facilities — for the first time ever.

New York City, which also received similar threatening emails, shrugged them off as bogus, a determination the FBI later agreed with.