POULSBO, Wash. - The Poulsbo Fire Department says a 7-year-old boy has died after being injured in an accident at a health club.

The Tuesday evening accident took place at Armstrong Fitness and Physical Therapy, where the boy's father reportedly was using a cable-crossover exercise machine.

Ann Armstrong, the owner of Armstrong Fitness, says she made it clear, children are not supposed to be in the weight area of the gym. But Tuesday night, a single dad working out had his 7-year-old son by his side when he somehow overpowered the machine and it fell over on his son.

The weight machine crushed the boy, who has not been officially identified. He was a first grader at Poulsbo Elementary School.

Parents were told of his death in a letter sent home Wednesday.

The department told the Kitsap Sun that the first-grade boy was pronounced dead sometime after he was airlifted to Seattle's Harborview Medical Center.

The King County Medical Examiner's Office plans an autopsy.