A 13-year-old boy was killed and 12 people were hospitalized when a visit to a hotels indoor swimming pool led to carbon monoxide poisoning, authorities said .

Several children had been swimming at the Quality Inn in Niles, Michigan, around 10 a.m. Saturday when a passing member of the hotels staff peered through a window and saw them lying unconscious on the deck, local fire officials said .

Six children between 12 and 14 years of age were rushed to local hospitals. One boy, since identified as Bryan Douglas Watts, died en route, local station WNDU reported .

Hotel staff members and police officers who responded to the emergency were also taken to area hospitals after being exposed to the toxic air.

According to WNDU, the CO levels were later determined to be 16 times the safe limit.