The 4-year-old boy, who was not identified, died suddenly on Saturday, Millville Public Schools said on its Facebook page.
The boy was enrolled at the district's Child Family Center, which teaches children who are three and four years old in Cumberland County.
"We extend our heartfelt condolences to the family during this difficult time and our thoughts and prayers will be with them in the days ahead," the school district's Facebook post read.
The boy was pulled out of a pool on Carmel Road at about 11:30 p.m., Millville police said. He was taken to Inspira Medical Center Vineland, where he was pronounced dead.
Elisabeth Corona, the district's crisis coordinator, can offer support to students and families. She can be reached at 609-501-5576.
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