A 10-year-old Iberville Parish boy was arrested Monday on one count of terrorizing after investigators determined he left a threatening voice mail at St. Joseph’s Academy in Baton Rouge over the weekend, authorities said.

The boy, who had no known connection to the school, was released to his parents’ custody, said Lt. Don Kelly, a Baton Rouge police spokesman. The motive for the threat remained unclear, Kelly said.

Law enforcement and school officials declined to discuss the nature of the threat, which drew a heavy police presence at a time of heightened concerns over school security. Kelly noted that “law enforcement must take every threat, regardless of how unlikely it may seem, very seriously.”

“The school decided to hold classes once they were assured by the mayor-president that a significant police presence will be assigned to the school for security,” Kelly said in an email.

Police and East Baton Rouge Parish District Attorney Hillar Moore III planned to meet with school administrators to discuss a contingency plan for security staffing. Moore said he was made aware of the threat over the weekend and met at the school Monday with law enforcement authorities.

School spokeswoman Mindy Averitt said St. Joseph’s arranged for added security the rest of the week, including plans to have a guard on campus.

“Tomorrow will be business as usual,” she said.

The decision to add security but keep school open Monday was made in cooperation with the Baton Rouge police, who reviewed the incident, Averitt said.

Parents were sent messages Sunday giving them the option of sending their children to school or allowing them to work remotely via laptop. Averitt said more than half of the student body attended school Monday.

Students who stayed home will be afforded an excused absence, she said.

“We thank our parents for their support and cooperation,” Averitt said in an email. “Please be assured that throughout the weekend and into today, we followed the advice of law enforcement officials and communicated as much as we could given the fact that the situation was an ongoing police investigation. The safety of our students, faculty and staff was always our top priority.”