NASHUA – Nashua High School North was secured in lockdown at 8:45 Monday and students were dismissed in early release at 11:30 a.m. after a single bullet was found in one of the bathrooms, according to an email to parents.

Superintendent Mario Andrade told parents: “All are safe and it is important to note that we are not in the midst of an active event.”

Andrade told parents that Nashua police are investigating.

“There were no threats or messages connected to the ammunition, and there is no known threat at this time,” Andrade told parents.

“We understand and respect that events like this can cause concern and many questions. We want to assure you that our students remain safe and supported. We appreciate the level of trust that is required in sending your children into our care and we want you to know that as educators and parents ourselves, we take that responsibility very seriously.”

Nashua Police Sgt. John Cinelli said it was a single round of ammunition found in one of the bathroom toilets.

“Our detectives are currently investigating and have not made any arrests,” Cinelli said.

He said he didn’t know if police have any suspects.