Supt. Richard Smith alerted parents about the 11:50 a.m. dismissal with a telephone call placed to the contact number parents have asked the district to use for such emergencies.

The phone system disperses a recorded message from a school administrator within minutes to as many numbers that parents have asked the school to use, so calls went out to cell phones, home numbers and work numbers, the superintendent’s secretary said this afternoon.

The dismissal was “in response to a new written threat that was found on school property,” Smith told parents in the first of two recorded messages he has sent out. “The threat is similar to the threat discovered earlier this month, in that it was vague, indirect and did not reference any individuals or groups of students or staff.”

In a follow-up call placed later this afternoon, Smith told parents and guardians that North Attleboro Police Chief Michael P. Gould Sr. reviewed the “written threat” and “assessed the nature of the threat.”

School will be in session tomorrow, Smith said in his second call. Parents will be contacted later today by High School Principal Robert Gay, he said, “who will be advising students and parents of any changes in procedures for tomorrow morning.”

In his first call to parents, Smith said: “I made the decision to dismiss school to err on the side of caution and to allow the North Attleboro Police to take action in conducting a search of the building, continue its investigation into the matters and to make plans for the reopening of school tomorrow.”

Smith declined to speak to projo.com today. His secretary said he would not be available at any point today to speak to a reporter.