SPRINGFIELD, Mass. — The Springfield superintendent of schools said Friday that the district has stopped all pool-related activities while it reviews the death of a 12-year-old boy in a swimming class.

Superintendent Daniel Warwick called the Feb. 15 death at Kiley Middle School an “unspeakable tragedy” and warned that Monday’s return to school after the February break would be extremely difficult. He said grief counselors will be at the school to help staff and students.

“Words cannot express our deep sorrow,” Warwick said in a statement.

Police said the boy died during a class that had about 45 students and two teachers. Officials have not released the sixth-grader’s name.

Hampden District Attorney Mark Mastroianni told The Republican that the ongoing investigation is focusing on whether there was criminal negligence or recklessness in the case. On Friday, Warwick said the state Department of Elementary and Secondary Education has verified the school was operating within prescribed guidelines for swimming curriculums.

Meanwhile, a state Department of Public Safety team inspected the middle school pool on Wednesday, five days after the death. The results of the inspection are expected to be made public this week.

In his statement, Warwick said that since the boy’s death a week ago, “there has been an avalanche of questions and concerns” from people desperate to understand what happened.

“As superintendent, I assure you I am just as desperate to learn the answers to those questions and based on those answers to make thoughtful determinations about what must occur next,” he said.

But he said it was necessary to keep details about the district’s review confidential, for now, to preserve the integrity of the investigation.

Warwick said his only concern as things move forward will be what’s best for students, but he cautioned, “The fact of this matter is that this process will require time.”