CLOVIS, Calif. (KFSN) -- Clovis police have confirmed a 3-year-old boy, who was pulled from the pool at Swim America during a preschool activity on Thursday, has died. Police are investigating exactly what happened to the boy.The swim school was closed on Friday, as were the associated dance school, tumbling school and the preschool the boy attended. His class came over for a swim in the preschool pool on Thursday, and the boy somehow ended up underwater in the bigger pool.The calm waters of Swim America turned turbulent Thursday as staff members tried to save the 3-year-old boy found underwater. Nobody seems to know how long he was in there after leaving his group of about a dozen preschoolers enjoying the waters of the 2-foot-deep kiddie pool."That's where we were trying to keep everybody, and obviously we had a problem and somehow missed this young man, and we're going to take a careful look at it," Swim America co-owner Rick Klatt said.Klatt also owns tumble America, Dance America and the preschool at Camp America. He canceled classes at all of them until Monday out of respect for the boy's family, and to give his own staff time to heal. But he himself is still on site, racking his brain to figure out what happened and how to keep it from happening again."We'll review everything internally from A to Z, and you know, hopefully we can find exactly what went wrong here because we don't know precisely what went wrong," Klatt said.He does know the boy ended up underwater in a far corner of the bigger pool, near a water slide. But he knows that's not enough, and he says his entire team is heartbroken for the boy's family."Ohh, our prayers and hopes and dreams just go to the family," Klatt said. "I can't begin to tell you how awful we all feel; our instructors and our staff and certainly my wife who has built this place to be a safe place and a wondrous place for young kids."Swim America has a camera focused on parts of the pool, but they discovered Thursday it was not recording video.Clovis police say it could be next week before they're close to knowing what went wrong.